I have two questions related to oil. Actually 3 questions.

At my local Walmart they have Rotella Synthetic 15x40 engine oil for diesel. They also have Mobile 1 synthetic which I run in my car. Mobile 1 says it's good enough for a diesel also but the Rotella is about $5 cheaper. Can I use either oil in both vehicles? I could save a few $ on oil for my car with the Rotella. Also what is the best oil filter?

What oil should I use in the tranny? I think it's the getrag 360 but it may have been changed. I heard it s/b synthetic gear lube but all I saw was real heavweight stuff. Shouldn't it be lighter weight because the bearings are preloaded in the Getrag?

Should I change the engine oil more often if I only do short trips around town? Should it be changed more often if I tow a 32' 5th wheel trailer?

 

search my user name i just did a big post on oil change. i used rotella from walmart, and fleetgaurd filters all around from genos garage.

as for changing it i think it would be personal prefrence but you may want to do it hourly rather than milage since you do short trips.


jiMMy

 

1: Unless the Mobil 1 is the "Truck and SUV Formula", it's not a diesel rated oil. On the oil bottle you use, there should be a little circle that says CI-4 in it. That's the current API spec for diesel oils. Rotella is a good diesel oil, but it does have a distinctive smell for the first 1,000 miles or so. The crankcase has an open breather tube so you will smell it. Mobil Delvac 1300 and Chevron Delo 400 are available at most Wal-Marts and don't stink. And the Mobil is usually cheaper than the Rotella. Diesel rated oils do a great job in gas engines - the additive package contains lots of detergents and extreme pressure compounds when compared to a gas engine oil. Rotella or any of the other diesel oils will keep your car's engine cleaner and can run longer between changes. The only downside is the heavy weight oil flows slower on cold starts and can make extreme cold weather starting difficult.

On the filter, I recommend Fleetguard, Donaldson, or Baldwin. If there's a heavy truck parts store in your area it will usually be the cheapest place to buy filters ($4.87 for Donaldson at Triple R near my job).

2: The factory spec for the Getrag is 5W-30 motor oil. Many people use Mobil 1 5w-30 and are happy with that, I am using Redline MTL. MTL is a synthetic oil of about the same viscosity as 5W-30, but it also has additives that help the synchros get better "traction" for easier shifting and longer synchro life. Costs around $7-$8 a quart at speed shops, Summit Racing can get it for you.

3: Yes. If the engine does not come up to full operating temp most of the time you should change more often than the factory 6 month/6k interval. Keep in mind that the Cummins has a water to oil oil cooler, as long as the coolant is hot, so is the oil, unlike most gas engines where the oil takes longer to heat up. My commute is 12 miles, the engine is up to temp by halfway most days. If your short trips are really that short, I'd say cut the factory interval in half.

No. It was made to do that. Towing makes for a happy Cummins.