Engine/Transmission (1998.5 - 2002) oil question

[satmike]

How many miles should I have on my motor before I change to a semi synthetic? I have 22,0000 mi. and want to make sure it's broke in.

Thanks Mike

 

[Rob Thomas]

According to Cummins', these engines require no "break-in" time, you should be all set to run whatever oil you choose.



Later, Rob

 

[JCyrbok]

my 2 cents

I'm going to full synthetic in another 900 miles which will be 20k total. I read somewhere, I think the owners manual from DC that if you tow alot u can change at 10k but if you dont u should wait until 20K for "full break in" I played it safe and waited. Going by that u should be A OK.



J-

 

[LSMITH]

My power and fuel economy improved up till about 55-60K miles then leveled off. Mine was not babied in any sense and still took 60K to be fully broken in. Unless going for extended drains or in true artic conditions I would stick with dino oil until at least 40K.

 

[DocStressor]

According to Cummins, 5K-20k miles of break in using conventional oil is recommended prior to switching to synthetic. The actual mileage depends on how you drive. 5K if you tow or haul and up to 20k if you do not.



http://www.cummins.com/na/pages/en/....cfm?uuid=0003D957-1D8B-19FF-982180C4A8F00000



Heat is required in order to "seat" the piston rings. What really happens during a proper break in is that the relatively soft metal ring material gradually flows and changes shape over time and forms complementary surfaces with the ring groves and the honed cylinder surfaces. Minor surface irregularities also wear off and become suspended in the oil as wear metals. If you run a fresh engine at consistent high speed, ring material can become deposited on the surface of the cylinders and result in glazing. When this happens, the engine tends to use oil, show increased blowby, and reduced compression. The opposite can happen when using synthetic oil during break in. True synthetic oils (Group IV and V) reduce friction and also carry heat away better than conventional oils. Thus it takes longer for the break in process to occur. There is some evidence that some engines continue to use oil if synthetic is used from the beginning. This is controversial and I doubt that even Cummins has data to support this notion. The oil companies say that this is not so and that synthetics can be used from the git go. This is certainly the case with high performance gas engines that are blue printed or run in at the factory on conventional oil. VW TDIs come from the factory with a Group III synthetic already loaded. But for a Cummins diesel, I would follow the factory recommendation just in case. The engine just does not get worked as hard in a pickup (most of the time) as compared to how it was designed. Consider a B series engine in a tractor or a garbage truck. I'm sure the break in rate is much faster in those applications than in ours simply because of the load (and heat) differential.



If you wait too long to switch to synthetic oil, you will lose the benefits of the more expensive lube. 20K is long enough no matter how you drive.



Sorry, I just noticed that you asked about a semi-synthetic. Forget everything I just said. You could have switched at any time. They only contain 10-30% synthetic base stock. Other than for better low temp flow characteristics, they are not much different than convention oils.