I just bought 8 quarts of Delo 400 for my '91 350SD. Even though my mechanic changed the oil last time with Red Line, I'm not really interested in leaving it in there for so long to justify the cost. What do you guys think? Am I on the right track? Should I stick with synthetic for the 350? I'm planning to change every 3-5k miles, so I'd rather not spend $100 on Red Line every time!

Tell me if this makes sense - I would like to run several oil changes to clean out the gunk that was in the engine when I got it. It looked like perhaps the PO put in some oil additive or something - my mechanic said the old oil came out like black honey. So, I would like to run a cheaper oil - at least for several changes - if that will help clean things out.

At 5K change interval, Delo 400 would serve you very well, if in doubt, get a oil analysis done for Delo 400 and Redile at 5K and get ready for a nice surprise.

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99 Gurkha with OM616 IDI turbo

2015 Gurkha with OM616 DI turbo

2014 Rexton W with OM612 VGT

The Universal grade oils are especially formulated for diesel engines and will serve you well. The common examples of these are; Mobil Delvac1 or Delvac, Shell Rotella T and Chevron Delo 400.

These oils have moly additives necessary for non roller cam followers and more importantly has large amounts of additives that are used for soot dispersal which is quite necessary in a diesel. There are many oils "rated" for diesels, but they are not especially designed for diesels. Stick with one of these oils and you will be much better off than with standard oils, even synthetic standard oils. If you are willing to pay big bucks for the ultimate diesel oil, use a synthetic version of one of the above.