i just swapped an lt1 motor in my 86 z28. Can i use synthetic 10W40 or should i go with 10W30 in it? Any help would be appreciated.

 

When you have a choice, go for the lighter oil. 10W30 is what was recommended for warm temps in LT1's.

 

you hear all kinds of stories.. and this is 1. . I once read that it is not a good idea to use 10w40 in vehicle engines because of the additives used to get the 10-40 split. I'm not asking for flames hear.. that's just what I read.. And personally, I just go with mobil 1 for brand.. and 10w30.. that's my pick, and everybody has a different opinion.

 

did you just rebuild the LT1? if so, you can't put synthetic oil in it. Use 10W-30. If not, the cylinders will never seal up with synthetic oil.

 

also heard that that doesn't matter either.. but I would save a few bucks put reg oil in and don't even think about synthetic until the 1st oil change.. my bad there.

 

I would use dinosaur sauce (read: mineral oil) for break in, because its not as good as synthetic. It will take forever to break in, if at all, with synthetic.

Break it in with regular oil, then use synthetic after break-in

 

ive heard ppl say to use non-detergent motor oil for break-ins that even todays regular oil is too good to use for breaking in a new motor

 

Thanks guys for all of your helpful advice.