hitmanws6

iTrader: (20)

Talked to my builder today about what oil to run after breaking in my 355 and he told me to run 50 weight oil. Common knowledge tells me to stick with a 40 weight at the most but what do you guys think? He is more of an old school builder, but he knows his SBCs very well. I was going to run 0W-40 Mobil 1 but after he told me this should I run 15W-50?

Rob94hawk

iTrader: (1)

If he built it then I would go by what he says that way if something happens you are covered.

brucer

i use 10w40 dino oil (i use to use rotella, it had zinc in it not sure anymore) for initial start up and break in, i use the cheapest filters i can find.
i do an oil change just after the initial start up.. basicly if the engines runnning good i will bring it up to temperature fluctuating the rpms.. i shut it off, let it cool off and change oil and filter again, usually check the filter for abnormal debris, start it back up, readjust valves.. i run that oil change about 250 miles,then i switch to mobil1 5w30 or 10w40 synthetic and a wix filter, drive that another 500miles and change oil and filter again.....


added this, if there is a written warranty use what he said and have receipts and a witness thats what you used.
if its a pavement warranty i would use a thinner oil myself to make sure the entire engine gets oil as quick as possible....

speed_demon24

iTrader: (6)

Listen to your engine builder since he setup all the clearances.

kinglt-1

iTrader: (26)

This!

96capricemgr

iTrader: (1)

Did he spec thick because he was not capable of setting up tight clearances???

Did he take into account the LT1 oil pump drive which is often damaged by HV pumps? Given that I would seriously worry about running 50wt in it long term as thick oil is undo load on the drive just like a HV pump is.

If he set it up for 50wt. you have little choice as it is too late now.

Most guys with modern knowledge though seem to like thin oils for less parasitic loss, at least at a modest HP level like this.

hitmanws6

iTrader: (20)

I think he said that because I told him I would be running nitrous, so he thinks I'm going to be racing it, but the clearances are still tight. I was leaning towards 0W 40 Mobil 1, there are too many grey areas for 5W 30 M1, everyone says wear is higher but at the same time I don't know anyone saying anything negative about it personally and the fact that GM uses it in all the LS motors from the factory, that can't be all marketing

brucer

dont forget ford, dodge, and mercedes benz also recommend mobil1 5w30.

Lonnies Performance

iTrader: (16)

If he means 20w50 or 15w50, I can see that with larger bearing clearances.

If he means straight 50, no way... That is retarded.
No need for thick as tar oils when cold. That is 1950's technology.

Wicked94Z

iTrader: (26)

who built it, and what are the clearances? not tight, loose, etc. ACTUAL numbers. dwayne were you going to include any actual technical information in your post or no?

hitmanws6

iTrader: (20)

I don't have #s but its a stock bottom end rebuild with ARP boilts/studs and the larger pistons as the only difference. Clearances are stock. I just talked to him, he was under the impression I was using is as a straight track car, he told me a 30 weight would be fine. Thanks guys

shbox

If it is stock clearances, then you should be running the same oil as OEM specified, IMHO.

TheDon619

iTrader: (4)

i used 20w50 to break in and 10 w 40 after breakin on my new 355 in the bird. and i got amsoil to put in it on the next change.