View Single Post
Old 03-26-2002, 11:53 AM
tcane tcane is offline
Senior Member
Join Date: Jul 2001
Location: San Antone
Posts: 408
Your results compared to what? A baseline is needed to know if your readings are normal or not. The baseline would have to come from the same type of engine run under controlled tests with monitoring to establish the relevant data needed to do further analysis. For example, Mack truck diesel engines in the 70's and early 80's would show large amounts of material from the bearings that in other diesel engines would indicate a failure was about to happen, if not already. However, these readings were normal for Mack engines. Except in the case of a really high reading that is so far out of the norm that a problem has to exist that should be repaired or something is found where it should never be (like coolant in the oil) a baseline is needed to do a valid comparison. As Jackd wrote, some key things were not tested. Also, the way the test sample was taken is at issue and will invalidate test results.

Here in San Antonio is located Southwest Research Institute that tests oils and filters for many manufacturers, including M-B (one of the premier testing facilities in the world, if not the best). I've used the info from Southwest to help with diagnosing problems in the past because there was a baseline database to use as a comparison point (as well as having some fluids tested by them). Recently, I was looking for info on M-B oil filters and came across a scientific paper presented or published by Southwest scientists (I don't recall which) about testing done on the oil filter for a late 1990's M-B. I did not pursue what this info was because it did not apply to what I was looking for - I suggest you may want to look for this info since it may help you with the knowledge you seek.

I completely disagree with Jackd about diesel engines not being as hard on oil as gas engines. Diesels have about a 20 to 1 compression ratio versus about 9 to 1 for gas engines causing a lot of force on the pistons, piston pins, rods, crank, engine block, etc. (listen to the sound of any diesel engine when its cold compared to a gas engine, all that noise from a diesel is about the force created from the combustion from the high compression ratio - anyone with knowledge will tell you that a gas engine with say a 12 to 1 compression ratio will not last as long as one with a 9 to 1 because of the strain the engine is under). This is why the diesel engine's components are built much stronger than a comparable gas engine (displacement, output, etc.) and the bearing surfaces are significantly larger (30% to 50%) when compared to gas engines.

The bearing clearances and piston clearances on M-B diesel engines are also much tighter than many Detroit gas engines - in fact the worn out spec for M-B diesel engines are close to the max spec allowed for many new Detroit gas engines. Tight tolerances means M-B diesel engines take longer to fully wear in and polish bearing surfaces such that particulates found in the oil reach a plateau - your engine should have reached this point or will so soon (depending on how the engine was broken in and driven since).

Also, diesels must use better oils than gas engines. Using an oil only rated for gas engines (using a very good oil filter to filter out damaging particles) will wear out a diesel faster than if an oil rated for diesels is used (all other things being equal). On the other hand, using a diesel rated oil in a gas engine (esp. the better dino diesel oils like Chevron Delo, Mobile Delvac, or synthetics with diesel rating like Mobile 1, Amsoil, Red Line, etc.) will lengthen the life span of a gas engine (all other things being equal).

My $0.02 worth!
America: Land of the Free!

1977 300D: 300,000+ miles

American Honda: Factory Trained Technician & Honor Grad.
Shop Foreman;
Technical Advisor to Am. Honda;
Supervisor of Maintenance largest tree care co. in US for offices in Tex.
Reply With Quote