Whats the thoughts on changing to a synthetic oil in an engine with 65000 miles that has been broke in on shell rotella ?

 

No problem but once you get up over 150k you run the risk of the syn oil cleaning up sludge depoists that were sealing leaks.

 

The engine will leak oil, cummins does not recommend it because of oil leaks.

 

From what I have read is the molecules are smaller than regular oil so it will go through places the normal oil wont so you get leaks.I switched in an astro van with 150,000 miles on it and it instantly started using oil,I tried mobil 1 ,5w50 i think .I switched back to regular 20w50 and it doesnt use a drop between changes.I have since switched to 15w40 diesel oil in it and its doing great,its at 180,000 now.

 

guess i will scrap that idea. thought it might be a good thing to do.

 

I run synthetic and dont have any extra leaks over regular Rotella . We've got a truck with over 500k on it, runnin synthetic, and not a single leak
Even if the truck did end up leakin a little oil, I personally think the benefits of synthetic highly out weigh a little lost oil . I can go way over 10k on an oil change (synthetic) and only ~4k on Delo via oil analysis.
Scott

 

I ran dyno oil until 150000 miles then switched to synthetic oil.....no leaks or consumption of oil 25000 miles later

If you have oil leaks now they will leak more with full synthetic there are some oils that are semi- synthetic that can be switched to without problems like Kendall SHP 15w-40

http://www.kendallmotoroil.com/content/hdeo.asp

http://www.kendallmotoroil.com/techd...HP_DIESEL2.PDF

 

Synthetic oil is is good to run in a engine that smokes because it does not burn, a easy fix for smog testing.

 

I switched to synthetic oil at 160K and have noticed any leaks or other problems. I am satisified with the results and would do it again.

 

installed Amsoil at 81000,and no probs at all.In fact, My mileage has increased,and it feels like it runs better.Didn't leak before,doesn't leak now.