I have heard that once you go synthetic you can't go back to petroleum based.

I jsut had a shop do a head cam intake swap and I am pretty sure they have to change the oil in the process (to lube up the roller rockers and valvetrain). I went to Mobil1 after i bought the car (15000 miles) and if they put petroleum based in will I have problems?

Then again i ahve headr of synthetic/petroleum blends. if worse comes to worse i can just change the oil within a day or to with me just driving it 3 minutes to the car craft shop on campus.


Thanks
--Dan

 

Whoever you heard that from is WAY OFF...

Synthetic oil MUST be compatible with conventional oil, it's a law.

Mixing the tow has no harmful effects whatsover.




HTH

 

1986 engine? Unless the shop installed a retrofit roller cam, I'd leave the mineral oil in until the cam is polished (run in), then swithc back to synthetic. There is no harm in mixing mineral oil into synthetic, or vice-versa, except for the reduced lubrication. There is far more danger in mixing two synthetics of different base types, since a POE and PAO base can react adversely, and virtually stop lubricating.

Run it for the first 500 or so miles (break-in) with the oil they installed, then switch the oil and ESPECIALLY the filter. Your existing filter should be just about crammed with particles by then.

 

doesn't hurt anything to switch back and forth or to mix the two.

 

you can go between the 2 no problem...as far as break in pretty sure you go with a petroleum oil..then you can switch over to a good synthetic. my humble opinion is use a good synthetic if the pocket book will allow it..the bonuses are extended drain intervals and better protection at all temps...later..

 

It's funny because before this site, I used to hear that all the time. How did this all get started.