Engine/Transmission (1998.5 - 2002) Dumb synthetic oil question....

[SLightfoot]

Well, I've always used regular oil in my Cummins since day 1.



I'm thinking now of switching to synthetics.



Are all synthetics good for both diesel and gasoline engines?



It seems standard dinosaur oils are clearly labeled for diesel or gasoline, but all the synthetic oils I look at in the stores don't indicate either way.



What synthetics should I use?



Thanks,



Shawn

 

[RustyJC]

A current diesel engine synthetic on a store shelf will carry the API "donut" symbol with a CI-4 or higher service rating.



Rusty

 

[2-ND TIME]

only dumb answers!

I have been using Mobil 1 for 20 years now. Do do your own research on the subject. They have 5W/40. Most have this or 0W/40 for diesel oils. You can pickup a product book form most of the oil companies that show the spec's and what they offer. I probably have 4 or so around somewhere some out of date by a few years.

 

[Diesel Nut]

Amsoil offers oils for both. Just look at its intended use. you should be looking at the 15W40 .

 

[BHartman]

Well, I've always used regular oil in my Cummins since day 1.



I'm thinking now of switching to synthetics.



Are all synthetics good for both diesel and gasoline engines?



It seems standard dinosaur oils are clearly labeled for diesel or gasoline, but all the synthetic oils I look at in the stores don't indicate either way.



What synthetics should I use?



Thanks,



Shawn

Rotella has a new syn. out 5W-40W. The dyno oil was wonderful and the Syn meets Cummins guidelines. It's about $5. 00 cheaper than Mobil 1 also and I know a lot cheaper than Amsoil.

 

[Diesel Nut]

Rotella has a new syn. out 5W-40W. The dyno oil was wonderful and the Syn meets Cummins guidelines. It's about $5. 00 cheaper than Mobil 1 also and I know a lot cheaper than Amsoil.

Its alot cheaper than Amsoil becasue its not a true Synthetic oil. It is by title becasue of a court case or something someone lost on what can be labled a synthetic, but when you read the MSDS it states right on it that it is composed of highly refined petroleum oils. Not Synthetic oils. So, in a sense, you get what you pay for. I'm not saying its bad oil I am just saying its not a good comparision.

 

[SLightfoot]

Thanks for the info guys.



I ended up going with Valvoline Premium Blue Extreme 5W-40 synthetic.

The guy at Cummins said that they've had good luck with it.



Thanks again.



Shawn

 

[Jeepmullet]

so umm... how far down does Amsoil crack their petrol derivatives so they can be called snythetic?

 

[Bernie]

Valvoline

I have used Mobil One for years in my gas engines (race and street cars). It is amazing stuff. A friend recently had a cooling system fail in his race car. He is an engine builder, and after doing a tear down he credits the Mobil One for getting him through.



I have been using the Valvoline Premium Blue (15W-40, dino) in my CTD. Per Cummins the first 20k miles should be run on dino oil. I beleive this is the same product that is sold as the "Mopar" brand of oil for the CTD.



However, I will be turning 20k miles on my 2006 CTD next month. Then I will be going with the Valvoline Premium Blue Extreme (full synthetic, 5W-40). It was engineered by Valvoline with input by Cummins, and meets their new low sulfated ash requirement. It also costs less than many of the other synthetic products. For my money, it doesn't doesn't get any better than having a product designed with Cummins engines in mind.



Keep in mind when you change to a synthetic on an older engine you may have a few small oil leaks appear. This happens for two reasons:

-The synthetic is a very good cleaner. It will clean gunk out of areas that might be leaking if it weren't for the gunk. (For the same reason I would also change the filter halfway through your oil change interval after you change to synthetic).

-It is thinner oil. It dosen't vary in viscosity as much as dino oil, so it starts out thinner.



For more info check out http://www.bobistheoilguy.com/

There will be more info there. Both fortunately and unfortunately, just like this forum, any user can add his or her two cents worth. As a result you get a lot of opinion mixed with the fact. Look for good technical descriptions (that aren't from individuals trying to sell you a product) and you should be fine.