Here is an interesting observation

[DValentine]

For those who may not remember, I replaced my head last February due to my own ignorant porting screw up on the stock head. I have been running a 5w-40 synthetic for a long time and ran it after I replaced the head. I had a fair amount of blue smoke at startup, say after a 6 hour or longer period of sitting. The last time changed oil, I couldn't get to town to buy the synthetic, so I grabbed Rotella 15w-40. Now after about 1500 miles on the oil I have noticed that the startup smoke has greatly diminished. Now mind you all this is not a scientific study..... it is what I have noticed. I know that one is advised not to use synthetic until a engine is broken in. Even with the new head, I sure didn't think about the oil I was using.





Any thoughts?



Merry Christmas (or happy holidays... if the previous offends :--)



Dave

 

[JLEONARD]

I have read before (several times) that switching to a synthetic "may" cause an oil leak... I suppose that leak could be internal or external... .

Jay

 

[DValentine]

Yeah Jay,

I've seen it in my pinion seals and such. I don't know if it is an internal leak. I'll know when I go back to syn next oil change.





Dave

 

[btoscano]

I have not experienced any new oils leaks with synthetics in any of the vehicles I have used them. In fact, a former 1987 Mercedes-Benz 190DT (2. 5 Turbo) had a leak out of the real main seal when I purchased it with 380,000 miles (yes, 380Kmi) I changed to syn lubes and drove the car to 320 miles round trip including WOT up the steepest interstate grade in the state. After that the real main didn't leak anymore. And, yes, the engine still runs good...



Brian

 

[Moab4x4]

I have used synthetic in a number of engines and have found that if the oil loss is due to worn rings & blowby then synthetic does not blow away as fast as dino oil. I had an old gasser that would use a quart of dino in less than 500 miles, but with synthetic it would go 2-3000 miles.

If the leaks are seals and gaskets however, the synthetic runs out a little faster than dino.



As to the new head issue with synthetic smoke... . My naive question would be How are the valve seals? It sounds almost like the synthetic is slipping down the valve stems and pooling in the valve area given time. With the new head hence new valve guides it sounds like the old dino doesn't want to slip on down.



Interesting observation indeed... .