Which Engine Oil (conventional or synthetic)

[WireBender]

I know this topic comes up from time to time but I am trying to decide which engine oil to use in my 2017 Silverado with a 6.6 duramax diesel. I've been using Mobil 1 in all of my gas engines in the past and have had good results so far. I am wondering if I should do the same with the diesel, or just go with the conventional oil. Full synthetic, synthetic blend, or conventional. Any thoughts?

[redwngr]

Semi-synthetic (blend) fan here, but you'll get lots of opinions.

 

If reading the diesel supplement, be sure you're in the section for the 6.6, not the section for the little diesels, since GM has a different oil recommendation for the 2.8.

 

Pick your favorite CJ-4 15W-40.

 

In Texas I would guess your not going to see extended periods of weather below 0F, but 5W-40 is the preferred oil for extended very cold periods. (and it can be used at high temps as well)

[Z45]

A new study by AAA puts to rest one of the most common questions car owners have Synthetic is better

 

 

 

In the study, AAA found that "synthetic engine oils performed an average of 47 percent better than conventional oils in a variety of industry-standard tests,” the organization's managing director of Automotive Engineering and Repair, John Nielsen, said in a statement.

[WireBender]

redwngr

 

Where I live it can be anywhere from below zero to above 100 degrees. You never know around here.

 

 

I am leaning toward going with the full synthetic and have been using Mobil 1 for several years. That narrows it down to:

 

Mobil 1 Turbo Diesel Truck 5W-40

 

Mobil 1 Delvac ESP 5W-40

 

Mobil Delvac 1300 Super 15w 40

 

I will check and see what is available and prices in my area. I think any of them would be a good choice. I was not sure if there were any downsides to using synthetic oil in the diesel engines.

[StinkyCheese]

I use 15w-40 Mobil delvac in my LMM. If you want to stay with Mobil and go synthetic Mobil has rebates on their oil once or twice a year. I think it's $60 back on a 5 gallon jug for the synthetic stuff. With the delvac I get $25 per bucket and I wait for one of the parts stores to have them on sale. After rebate I pay only about $70 for 10 gallons of oil. Florida doesn't get cold so I really don't need the synthetic. Ran Mobil 1 on my 6.0 2500HDs. Just can't justify the cost difference for synthetic on this truck.

 

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[WireBender]

I use 15w-40 Mobil delvac in my LMM. If you want to stay with Mobil and go synthetic Mobil has rebates on their oil once or twice a year. I think it's $60 back on a 5 gallon jug for the synthetic stuff. With the delvac I get $25 per bucket and I wait for one of the parts stores to have them on sale. After rebate I pay only about $70 for 10 gallons of oil. Florida doesn't get cold so I really don't need the synthetic. Ran Mobil 1 on my 6.0 2500HDs. Just can't justify the cost difference for synthetic on this truck.

 

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I know what you mean about the cost. I have been driving at least 160 miles a day for the last four years so my oil changes are often. With this truck holding 10 quarts of oil I will be looking for every discount I can get.

[Black02Silverado]

Oils of today are pretty good. Not like in years past. For the price difference I would go with a Synthetic. Just better protection and cleaning and in a diesel that is important. Also if you still have all the emission stuff on then you could have fuel dilution in the oil form when it regens. There again, a synthetic would handle that better.

[StinkyCheese]

 

I know what you mean about the cost. I have been driving at least 160 miles a day for the last four years so my oil changes are often. With this truck holding 10 quarts of oil I will be looking for every discount I can get.

 

Shell has rebates on their rotella as well. Price between rotella and mobil seem pretty equal with rebates and sales. Probably can't go wrong with either of them. Engine oil is the cheap fluid change. As far as I know they don't have rebates on tranny fluid and the stuff for the differentials. If they do then dangit where were they 2 weeks ago when I changed those fluids lol

[WireBender]

Thanks for all of the replies. Some good information here. Most just reinforces what I already thought but I am one that likes to research things before i do them and I am always looking to learn more.

So far I like this truck a lot. I have had several over the years but this is my first diesel and since I am a DIY kind of guy, I am trying to learn as much as I can.

[smith462]

I have been using Amsoil in my 2015 since new and change it every 10,000 miles with absolutely no issues in 90,000 miles.

 

 

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[Peterd]

 

Have used 15w-40 Mobil Delvac !300 Super, change every 5,000 miles. Why change what works?

 

Finding it at reduced cost has proven difficult

[pogrelis97]

I ran Schaffer's oil and changed it every 10,000 miles on my 05 Duramax, put 150k on that truck with no issues. I plan on trading in my 2016 before I put enough miles on it to run out of free oil changes so whatever the dealer uses is fine for this truck.

I'm a believer that as long as you change the oil when recommended by the manufacturer that you'll be fine no matter what brand oil you use.

[txab]

Shell Rotella T6 Full Synthetic

[Loco-diablo]

My buddy runs Rotella in his fleet of duramax diesels including his personal ride, a 2017 Denali HD. He swears by the stuff.

 

 

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[OpsWest]

I usually get the best and add a XX micron bypass filter. Injector dependency is crucial over long period - at least at last check from engineering perspective.