Change Oil Or Not?

welscher08 · March 21, 2010

Everyone, I want your opinion on this. The truck is a 2003 RCSB. I had the oil changed in October of 09. Right now the truck has 39,871 miles on it. The dealer put in the window to change the oil at 39,866 miles. So I am just slightly past this, and my Oil Life Monitoring is at 18%.

I told the dealer to put 5-30 Mobil 1 Synthetic in it, and on the slip from the dealer it states they did. But from what I had read I thought the OLM system can tell the difference between dino and synthetic oil and would go down accordingly. So being at 18% right around the 3,000 mark shocks me some. Do you think the dealer put regular oil in?? I do live in Minnesota, so this could/would make the OLM go down somewhat faster, but I usually started the truck and let it warm up. I know the OLM system takes all that into account and the idle time, etc. I do drive about 15 miles to work one way and then home, so the shorter trips might be to blame. I had planned to run synthetic and then just change oil twice a year, every six months, and figured for what i drive that would be about right. I know its not near the mileage you can run on synthetic.

So what do you guys think, run the oil to 5,000 miles, or change here sometime in the near future? Thanks!

MNfreak · March 21, 2010

go with what your truck says, thats why it's there. you can't hurt anything by changing it early anyways

MarkD · March 21, 2010

Are you planning to change it yourself this time, or have the dealer do it again?

RVJ · March 21, 2010

I don't think the O.L.M. can tell what kind of oil is in the truck. Someone might say I'm wrong though.

700 sportsman · March 22, 2010

I personally never use the OLM, just about 3,000

welscher08 · March 22, 2010

Are you planning to change it yourself this time, or have the dealer do it again?

Well I could do it myself I suppose, have before on my car. Just my 'nicer' vehicles i have always taken it to the dealer for them to service. I am tempted to take a sample of the oil and send it Blackstone Labs and have them analyze it, see what I get for results.

I know thats what the OLM system is there for....but still...I am curious if it can tell what type of oil is there or not.

I was just over at my friends house helping him move in a new safe he bought, and he has an 04 Duramax and I asked him if he goes by the OLM and he said yep, and then I looked at his. His has 45,xxx on it and the oil was changed at 42,xxx and he still has 65% oil life yet! Well mine is right at 3,000 and at 18% so what gives? I think i will schedule an appointment here before my Blackbear tune in April and have it changed and see. This is my first full oil change since i have owned this truck, and see who round two goes.

rodram · March 22, 2010

OLM has no idea what kind of oil (viscosity grade or dyno/synthetic) ... the computer monitors the number of revs in the engine, the time the engine is running, the temperature of the engine while it is running, and likely some other relevant parameters....

I assume that GM assumes that you will be using the specified dyno oil in your manual. so if you are using synthetic you might feel OK stretching out the oil change interval, but that is our choice.

Most people either have a specified mileage on the odometer to change or they wait until the OLM tells them to. My truck ('97) does not have one, but I don't put a lot of miles on it, so I make sure it gets changed in the spring and fall with synthetic (just my choice of oil). The OLM on my 2002 Impala used to light up somewhere between 9000 to 10,000 kilometers, and that seemed OK to me to change the synthetic oil..

welscher08 · March 22, 2010

OLM has no idea what kind of oil (viscosity grade or dyno/synthetic) ... the computer monitors the number of revs in the engine, the time the engine is running, the temperature of the engine while it is running, and likely some other relevant parameters....

I assume that GM assumes that you will be using the specified dyno oil in your manual. so if you are using synthetic you might feel OK stretching out the oil change interval, but that is our choice.

Most people either have a specified mileage on the odometer to change or they wait until the OLM tells them to. My truck ('97) does not have one, but I don't put a lot of miles on it, so I make sure it gets changed in the spring and fall with synthetic (just my choice of oil). The OLM on my 2002 Impala used to light up somewhere between 9000 to 10,000 kilometers, and that seemed OK to me to change the synthetic oil..

Thanks for the reply, and from everyone else also. That makes sense then, why my friend's is different though i don't know, unless the Duramax has different programming which it very likely does. But I thought I would run the oil 5,000 miles since synthetic, or 6 months. Thats only 2 oil changes a year for me, so this is what i will be doing. This has been my daily driver throughout the winter, so now when i get my car out and motorcycle this summer, the truck will get less miles on it, so synthetic is probably a waste for me and the mileage i put on.

bluArrow · March 22, 2010

Duramax has a larger oil volume as well as a standard oil cooler. That undoubtably figures into the longer oil life. Duramax also turns lower RPM's being a diesel so there would be less wear to deal with.

wrench57 · March 22, 2010

There were 5 Duramax's at the company where I worked in construction and I changed the oil on all of them between 9000-10000 miles. This was recommended by the dealer and we thought he was nuts. We ran independent oil samples thru our oil supplier on every change and they always came back good and this was running in const. conditions. The diesel will have a longer life than the gas rigs but the new gas rigs we were running we could extend the change intervals over the older ones. Most oil suppliers and or dealerships should have access to the oil sample labs [at a small cost of coarse] and to put your mind at ease you may want to have a sample ran at different mileage intervals and this would tell you the maximum oil life that you have. Keep in mind to use the same oil and filter all the time because there is a difference in them and how long they can go.

Z45 · March 22, 2010

I thought the OLM system can tell the difference between dino and synthetic oil and would go down accordingly.

No

From GM technical article...

NOTE: Synthetic oil resists "wearing out" better than mineral oil, so the oil life monitor is set to account for this, but only on vehicles that are specified for synthetic oil from the factory -- the Corvette, for instance. Using synthetic oil in other vehicles is certainly not harmful, but the oil life monitor will continue to count down as though the engine contained
mineral oil.

kawtoy_77 · March 22, 2010

I change it every 3k..... I tell the truck what to do, not vice versa.

FarmerDave · March 22, 2010

Yeah I don't use the OLM either, oil changes are cheaper than a new engine.

Major_Kong · March 22, 2010

I change it every 3k..... I tell the truck what to do, not vice versa.

That's great!

welscher08 · March 22, 2010

Thanks guys...Well I think I will get it changed here in April then, and just for the heck of it take a sample and send it off, since I got the free kit from Blackstone Labs.

I just need to decide to run syn or just go back to dino and change every 3k. In the MN winters though i think the syn would help. Thanks again though everyone, I appreciate it!