What oil are you running in your CRD?

jlg89 · **Posted:** Thu Apr 25, 2024 9:59 am

I've been running the "forum-recommended" Shell Rotella T6 15W-40 for years, but Mobil 1 has a Turbo Diesel Truck 5W-40 that looks promising. I plan to give that a try. Anyone have any experience with this or others? I'm in south-central Texas, so relatively warm climate, though we've had some colder-than-normal winters the past few years (i.e. we actually had several hard freezes).

WWDiesel · **Posted:** Thu Apr 25, 2024 12:10 pm

Best to stick with the Shell Rotella T6 15W-40 for warm weather operation.
Shell Rotella also makes a T6 5W-40 if you want to run a lighter weight during cold low temperatures.
I run the Rotella T6 15W-40 year round even during occasional low winter time temperatures with no issues. :wink:

taroo · **Joined:** Sun Apr 27, 2008 2:14 pm **Posts:** 285

I have only used Mobil Delvac ESP 1 (5W-40). Hope I am not screwing up!! I change every 4,000 miles.

jlg89 · **Posted:** Tue Apr 30, 2024 9:33 am

There's an interesting series of "shootout" videos on YouTube that use simple but consistent and effective tests to rate various synthetic motor oils at various viscosities. Mobil1 consistently scores very high, if not tops, even against top European and Japanese oils, as well as "boutique" oils.

https://www.youtube.com/@NATESINTERACTIVEAUTO/playlists

The real question in my mind is which specific weight to use. When I run 15W-40, the Libby tends to burn a decent amount of oil. I also drive a MB ML350 with the V6 turbodiesel, and it does the same thing with 15W-40...but it doesn't go through 5W-40 nearly as quickly. My Diesel mechanic confirmed that behavior, and said that the ML really prefers 5W-40. The Liberty might prefer 15W-40, but I want to see what it thinks about 5W-40, and whether it burns less oil with the lighter weight.

WWDiesel · **Posted:** Tue Apr 30, 2024 2:45 pm

jlg89 wrote:

There's an interesting series of "shootout" videos on YouTube that use simple but consistent and effective tests to rate various synthetic motor oils at various viscosities. Mobil1 consistently scores very high, if not tops, even against top European and Japanese oils, as well as "boutique" oils.

https://www.youtube.com/@NATESINTERACTIVEAUTO/playlists

The real question in my mind is which specific weight to use. When I run 15W-40, the Libby tends to burn a decent amount of oil. I also drive a MB ML350 with the V6 turbodiesel, and it does the same thing with 15W-40...but it doesn't go through 5W-40 nearly as quickly. My Diesel mechanic confirmed that behavior, and said that the ML really prefers 5W-40. The Liberty might prefer 15W-40, but I want to see what it thinks about 5W-40, and whether it burns less oil with the lighter weight.

A big problem with the oil tests link you shared; there is NO comparison of API "Diesel Rated" oils that I could find, all their tests are on oils for gasoline engines.
If you are using 15W-40 full synthetic oil in your CRD, be darn sure it is a API Diesel Rated oil, CH4 or higher; preferably CK4 is best.
Using a Gasoline rated oil in a diesel engine is a recipe for disaster! :grim:

Note: I run Shell Rotella T6 Full Synthetic 15W-40 oil year round in my CRD and have never had to add any oil between oil changes performed every 5k miles.

Some of the better oil recommendations for your Diesel engine:

DieselJeepLuvr · **Posted:** Tue Apr 30, 2024 3:03 pm

I've been running Mobil 1 synthetic in everything including my lawn mower since the 80's I've never had an oil related failure ever. I always run Mobil 1 5w-40 diesel truck formula in the Libbys.

mrhemi · **Joined:** Tue Dec 08, 2015 10:46 am **Posts:** 181

I have been running Rotella T6 5W-40 for over 300000km in one CRD and over 100000km in the other CRD with no issues. Change every 10000km as per FSM. Not going to mess with success.

What oil are you running in your CRD?

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