What 5W-30 oil brand are you using for the 6.6L gas?

[Chuck FB]

11 hours ago, revrnd said:

 

I see

 

Looking @ my manual, I saw this:

 

I dont recall seeing this concerning past trucks. It may have been in the manuals, but I ignored it since it didnt apply to me.

 

I wonder if this recommendation is more for trucks that aren't able to utilize a block heater which comes on @ -18* C/ 0* F?

When I saw that it reinforced my thought pattern all along from using 0W-30 in the past, that it has its place and while Mobil for example claims it can be used anywhere a 5W-30 can be used, I do still have to wonder if it is less sheer stable and only by testing used oil samples would one find out one vs the other within that brand of oil. 

 

It was not cold enough with the goofy temp sensing cord later in the winter for my block heater to even come on but my thought is that with what I see as a pretty sad excuse for a block heater capacity of only 400 watts I believe, that would have a harder time warming up the engine oil by way of radiated heat from the block above vs a much more substantial block heater wattage. Mind you if one installed a pan heater and like the block heater gave it time to warm the oil then that would solve any cold weather issues as far as the oil goes. The problem is when one can not plug in period, there is no place to plug in and your counting on the fluids to flow and hopefully that the engine will start at all, that is the moment when the best cold flowing oil is the right oil. 

 

You had made the comment about businesses having plugins for their employees, well in theory that sounds great and is a theme at some businesses but not at others. I find in town in talking to people that there are a lot of businesses that are not set up with parking for their employees and no places to plug in even if they have a so called employee designated area to park. So an employee leaving home in the morning with a vehicle that was plugged in and they get to work, typically if its nasty cold out they are forced to start and warm up their vehicle at noon for example so that by the end of the day the vehicle will start. Even with a block heater in some of the stupid cold days we can get, the engine is still not very warm and have to warm it up to clear the windows and warm enough to drive it but then doing that two more times without even being plugged in during the day and then just driving part way across town home, not good for the oils life or the engines !. 

 

Just to add here, at the dealership I had bought an extra plug in cord so that I could have one packed in the truck and not have to always pack up the one I have at home to throw into the truck. Their comments at the parts counter were "your new truck comes with one" and I said yes it does, I want a spare one. They then said oh yes that's good and by the way these are a hot commodity, guys come in here every so often buying them because some Ahole stole theirs where ever they were plugged in, apparently its a bit of a theme and becomes an expensive one as they don't give these cords away. 

Edited September 26, 2025 by Chuck FB

[revrnd]

1 hour ago, Chuck FB said:

Two items that make one question the thin viscosity theme, GM coming out with their scheme of authorizing the use of 0W-40 in the years of the affected 6.2 engine as they would not have done that if they didn't think the thicker oil was not going to help keep the crankshaft from dragging on its plain bearings. Or that while half ton pickups typically are calling for 0W-20, most heavy duty gas trucks call for 5W-30 or I believe the Hemi 6.4 recommends 5W-40 or at least they used to. If the thin oil was the new "it" miracle oil, they would have no reason not to recommend it in the HD trucks but they don't for a reason, of course the manufactures certainly don't tell us what that reason is because if they did that might put a little cloud over the thin oil theme. 

I dont recall what I was using in my trucks in the 80s & 90s, but would it be safe to say that 10W30 was the recommended oil for the old school small block Chevy motors back then? I think in 2000 when I got my 1st truck w/ the 'LS' motor, 5W30 was the recommended grade. I'm pretty sure conventional or synthetic wasn't specified @ the time.

 

 

 

[Chuck FB]

1 hour ago, revrnd said:

I dont recall what I was using in my trucks in the 80s & 90s, but would it be safe to say that 10W30 was the recommended oil for the old school small block Chevy motors back then? I think in 2000 when I got my 1st truck w/ the 'LS' motor, 5W30 was the recommended grade. I'm pretty sure conventional or synthetic wasn't specified @ the time.

 

 

 

I would have old operators manuals around ( actually in their vehicles .. we have some old farm beater trucks ) that would say whatever viscosity they recommended at the time but I believe 10W-30 seemed to be the main theme although at some point which I am not sure of either it evolved into 5W-30 being the go to viscosity but typically a manual had a graph that showed the operating range for various oil viscosity's and then said what minimum spec it must meet which was lets say SE etc. I will rattle off some information taken out of an old operators manual and many will have seen this in the past but might be amusing for some. 

 

I am looking at a manual from 1978 for GM 1500 through 3500 trucks ( except diesel it states ) and it blows me away that it states for light duty-change oil every 7500 miles and change the oil filter every other oil change unless one year has passed, then change the filter. Heavy duty truck every 6000 miles. But then goes on to say for both light and heavy duty trucks to change the oil every 3000 miles if driven in dusty areas, pull a trailer, idle for long periods of time, drive for 4 miles or less in freezing weather. My living on a farm, every crappy thing applies so 3000 miles it was and why my line of thinking may be different then some who rarely left the pavement. Also it states, after driving in a dust storm change the oil and oil filter as soon as you can, that's an interesting statement !. 

 

Oil Viscosity; Use the chart to select the proper oil thickness ( called viscosity or SAE Viscosity Grade ) for the temperature range you expect before your next oil change. They do not say anything about synthetic oils as that was not even on the radar for most people back that long ago. They show some straight weighs and then various multi grades, 10W, 20W-20, 30, and going from 5W-20 on up to 20W-50. A couple of very interesting items to note though, for the 5W-20 on the graph they show up to an ambient temperature from colder than -20f to a high of 20f while they show 10W from a low of 0f to a high of 60f. Also the 5W-30 is from lower than -20f to a high of 60f. The 10W-30 from 0f to above 100f. So from their standpoint with conventional oil they didn't seem to have faith that either a 5W-20 or 5W-30 could withstand the heat and basically pointing to running 10W-30 or 10W-40 or higher viscosity's yet during the summer time. Then it has a warning "Notice: Do NOT use 5W-20 oils for continuous high speed driving". That is interesting, I can only guess that either they had tested that and found out its lackings or that perhaps that oils viscosity broke down quickly and became very thin and that the 5W-30 was somewhat underwhelming as well. Oil technology has changed since then and the fact that part synthetics came out and then full synthetics became a lot more mainstream in the last number of years would have better cold and hot protection properties vs those multi grades from the 1970's technology. 

 

Now these days with GM and this Dexos certified theme, I haven't come across a 10W-30 that meets the dexos official approval. I am only speculating that they don't bother applying to meet it with testing because GM is pushing the 5W-30 and the 0W-20 theme. Same would go for 0W-40 or 5W-40 that may actually meet the chemistry requirements due to the low speed preignition issue of direct injection for European direct injection vehicles but why bother spending the money if GM is not saying one can even run a 40 weight oil. No doubt far more politics and bs going on vs actual best case protection of the engine in extreme hot conditions is my guess when it comes to the 0W-20. Logic seems to have faded into the background these days on so many matters in favour of lunacy ....  

 

Comment, hopefully it can be determined what I voiced personally vs what I simply typed down from what their statements in the book were.  

Edited September 26, 2025 by Chuck FB

[Chuck FB]

To add a much shorter comment as per a 1995 GM manual, it states the same engine oil change intervals ( as the 1978 manual did ) based on light and heavy duty trucks as well as the 3000 mile for dusty, towing, cold with short runs etc although now it states to change the oil filter every time !. 

 

The spec of the oil is now an SH 

 

For light duty truck they show 5W-30 and 10W-30 but say the preferred oil is 5W-30

 

For heavy duty truck they show both 5W-30 and 10W-30 but now the 10W-30 becomes the preferred oil viscosity to use. 

 

So that is definitely a change in how they view the 5W-30 but they still push for the 10W-30 for heavy duty use. I didn't see anything about the use of synthetic oils, I would have thought they would at least comment on it but I don't see anything. 

[Grumpy Bear]

10 hours ago, Homer1959 said:

I like to believe that the oil will have more chance to die as a 30 than as a 20 

 

Wear and oil induced friction are not related. Viscous drag is what happens to the oil. Wear is what happens to the machine. 

 

I'm not quoting the guy you quoted. 

[Homer1959]

4 hours ago, Grumpy Bear said:

 

Wear and oil induced friction are not related. Viscous drag is what happens to the oil. Wear is what happens to the machine. 

 

I'm not quoting the guy you quoted. 

Are you saying that wear can't be reduced by using a more viscous oil with a similar additive pack (to a point)? I'm not arguing, as I don't have the tools or knowledge, but if engineers recommend a W30, I personally prefer my oil to stay within that range and not drop below it. If that doesn't matter, why not just recommend a W20 from the start?

[revrnd]

Just looking @ 2 cans of 10W30 from back in the late 70s/early 80s that have been kicking around our garage for like forever.

 

The Gulf (disappeared after purchased by Petro Canada) can has an API rating of SF/CC. The other branded William Penn/BP (another long gone brand here) has an SE rating. Obviously those oils were from the era of 3000 mile/5000 km OICs. 

 

Then as someone surmised, once synthetics became more common, the OEMs found the 5W30 was suitable.

 

As I said earlier, there was no mention of whether to use conventional or synthetic. I figured if I was going to follow the OLS, I'd best use synthetic. Flame away, but w/ the mileage I was putting on my '95 K1500, it was nice to not have to spend so much time & money changing oil...

Edited September 27, 2025 by revrnd

[Chuck FB]

An interesting item and one can see the trend with the GM 5.3, is that the older 350 engines and I am not looking at some data base that might exist which would show the trend better from the very introduction of the 350 but in my example of the 1978 half ton pickup, it holds remarkably little oil as in around 4 quarts vs a 1980 half ton that holds around one quart more. I had a 1982 Toyota pickup that held about the same amount of oil in its 2400 cc engine as that older GM 350 does. The 1995 model 350 is around that 5 quarts but these days the 5.3 is at 8 quarts. The old 350 did not make the power of today's engine as per the cooling requirements but that little amount of oil and claiming 7500 miles of so called normal driving conditions with the additive package they had in the 1970's ... well maybe they were banking on the many quarts of "makeup oil" to keep the additives up !. 

 

Speaking of synthetics being so common place these days and in fact it would seem that dexos ( however good or bad those specs are ) is always a synthetic to make the dexos specs. Yet Ford to this day still is flogging their part synthetic dealer oil and that does seem odd given the small displacement twin turbo engines they have in so many of their cars and trucks and suv's as I would have thought they would insist on full synthetic of some fancy spec with such cookers of oil under the hood. 

[Grumpy Bear]

21 hours ago, Homer1959 said:

Are you saying that wear can't be reduced by using a more viscous oil with a similar additive pack (to a point)? I'm not arguing, as I don't have the tools or knowledge, but if engineers recommend a W30, I personally prefer my oil to stay within that range and not drop below it. If that doesn't matter, why not just recommend a W20 from the start?

 

No, not what I'm saying. You either have enough to limit wear or you do not. Viscosity is a measure of the fluids INTERNAL friction. (not yelling, emphasizing). More viscosity = more internal friction = mpg loss. Less viscosity = less interna friction = mpg gain.   Even this is not set in stone. You can have a oil with great lubricity that performs better in economy than a thinner oil of worse lubricity. 

 

Wear is independent of economy but not independent of viscosity. Think of it like this. Friction has two causes. Viscosity or internal fluid friction OR metal to metal contact. Getting drug across concrete. If the cause of friction is only viscosity then less friction = more economy with no to little effect on wear. IF however, the cause of friction is metal to metal contact then more viscosity = BOTH more economy and less wear. You have to know the CAUSE of the friction not just than it exists. 

 

Old time rule of thumb. If more viscosity = less bulk oil temperature then you have reduced wear by eliminating contact. IF more viscosity = more temperature then you have reduced economy with little to no effect on wear. The obverse of these conditions is also true. If a lighter oil increases bulk oil temperature then you've run afoul of contact and both wear and economy will suffer. If a lighter oil cools the bulk temperature then you increase economy with no to little increase in wear. This is only a rough rule an insist on a apples to apples oil comparison. I.E. same lubricity. 

 

This may seem confusing but if you read it a few times, close your eyes and visualize it...it will come to you. 

 

More times than I care to count, increasing viscosity lowers bulk temps and improves economy. On the rare case that this increase increases the bulk temperature it rarely lowers economy and I take the win. I'm never in a hurry to see how close I can get to falling off the cliff. In fact, I preferer this scenario. Gives me some breathing room for dilution and running hot and fast if the need presents. 

Edited September 28, 2025 by Grumpy Bear

[Grumpy Bear]

1 hour ago, revrnd said:

 

The Gulf (disappeared after purchased by Petro Canada) can has an API rating of SF/CC.

 

Off topic but in the States, Gulf assets were bought by Chevron USA while I was working at the El Paso plant. 

[Chuck FB]

I am not sure if it was Castrol or another oil brand that had a commercial that was advertising their oil and about maintaining the wedge as per holding the crankshaft up on the film of oil when the engine is under high load and the oil hot and that their oil resists sheer/viscosity break down etc etc. Fast forward to today and these thin oils they insist must be used in some engines and I wonder how close they are cutting their wedge, which again really makes me wonder when I see various brands of engines that insist on 0W-20 oil and long drain intervals and engines turning bearings or literally coming to a halt as the crankshaft siezes in the journals. 

 

Something I was thinking of lately and I believe there is some graph that shows crankshaft rotational speed and how that relates to maintaining a safe oil wedge and what I believe it demonstrated is that high load at low rpm is where the wedge is more vulnerable vs at a more moderate rpm with also the benefit of more oil volume from a faster rotating oil pump providing a higher pressure/flow of oil to the bearings. 

 

Relating that to more current engine designs, even the non turbo gas engine with its variable valve timing is allowing the engine to create more torque at a lower given rpm, same for the turbo gas engine only much more so with the amazing amount of torque those small engines can produce at such low rpm. Put thin oil in that engine and running hot under a sustained low rpm high load demand ( dragging a trailer up a Colorado pass mile after mile ) and lets say the oil already had many miles on it and has sheered down, it does make one wonder of the potential for damage at lower engine speeds. 

[revrnd]

I think it was Castrol. TBH I dont recall many oil commercials here over the years.

[Grumpy Bear]

1 hour ago, Chuck FB said:

Something I was thinking of lately and I believe there is some graph that shows crankshaft rotational speed and how that relates to maintaining a safe oil wedge

 

[Grumpy Bear]

Oil gets complicated only when one tries to distil it to an axiom.  It isn't a cosmic singularity. It is multifaceted, yes, but viewed from thirty thousand feet it makes perfect sense. Every chemistry is a compromise that demands corresponding operational accommodations. OEM's and blenders attempt to convince one that no concession is required. Wishes are not reality nor can they be. By and large the result of comprises that were made before you cracked the seal on that bottle. Ones you would not have made as an owner/operator whose goal is quite different from the OEM or blender. 

 

There could be some truly exceptional choices if cost/margin/profit/greed could be removed from the equation by the OEM, the blender and the end user. If performance was the only stick of measure by all parties. that dog WILL hunt. 

 

Since we can't have a perfect lubricant we have to choose or create the perfect situation for what is available. This is going to mean NOBODY gets their best economic solution or at minimum their way, based solely on the cost of the lubricant or the margin hoped for, but the owner/operator can have a darn good mechanical result and a very happy powertrain. 

 

 

 

[Chuck FB]

9 hours ago, Grumpy Bear said:

Oil gets complicated only when one tries to distil it to an axiom.  It isn't a cosmic singularity. It is multifaceted, yes, but viewed from thirty thousand feet it makes perfect sense. Every chemistry is a compromise that demands corresponding operational accommodations. OEM's and blenders attempt to convince one that no concession is required. Wishes are not reality nor can they be. By and large the result of comprises that were made before you cracked the seal on that bottle. Ones you would not have made as an owner/operator whose goal is quite different from the OEM or blender. 

 

There could be some truly exceptional choices if cost/margin/profit/greed could be removed from the equation by the OEM, the blender and the end user. If performance was the only stick of measure by all parties. that dog WILL hunt. 

 

Since we can't have a perfect lubricant we have to choose or create the perfect situation for what is available. This is going to mean NOBODY gets their best economic solution or at minimum their way, based solely on the cost of the lubricant or the margin hoped for, but the owner/operator can have a darn good mechanical result and a very happy powertrain. 

 

 

 

While its probably always been a game for oil blenders to hype up their oil with claims that are stretched vs the truth to make sales, now to add to the outright lying are entities that probably have politicians in their pocket calling the shots and forcing the concept of thin oils with long oil change intervals along with all the garbage they have invented to strap onto diesel engines that just kill them. "they" are certainly not doing what is best for the mechanics of the engine and that is what pisses me and many others off. However like you state, that's why the conversations like this come up over what oil may be better to use viscosity or chemistry wise and what oil change periods allow the engine the best reasonable life vs what the manufacturer claims is sufficient ( to get past the warranty although they don't spell that out obviously ).