Is 5w/30 ok for new 351W

[OsideDave]

I have always ran 30w valvoline in both my older vehicles w/ good results. Seems like 30w is disappearing from the shelves at a lot places, should I switch to a multi-weight motoroil like 5 or 10w/30 or something else for my new 351w w/ approx. 370HP?

 

[gjrock]

Call the shop you got it from.Did they send you break in instructions?

 

[ugly74]

for a new engine, with tight tolerances, 5-30 or 10-30 should be fine.
I've always run 10-30 in all my engines.

 

[needabronco]

I usually run 10/30 in mine or 20/50 depending on the time of year I change my oil. I drive so little it's more like an annual tradition now%)

 

[rcmbronc]

If it is a new motor with a flat tappet cam I would break it in with 15W-40 Rotella diesel oil. Then switch to 10W-30 after that.

 

[Scrapper_MV]

Just make sure the oil has zinc in it. Especially if it's got a new flat tappet cam! I like Brad Penn racing oil, but it's hard to find. Second choice is VR1 by Valvoline, it's a lot easier to get and it has the zinc. You can go to a GM dealer and get EOS and add it for the cam break in. Multi Viscosity is good if you live somewhere that gets cold.

 

[Broncobowsher]

For a fresh tight engine, 5W30 is fine. I run that in my stroked 5.0 and with correct tollerances and a stock volume oil pump the oil pressure is always fine. On my old car I lost about 2MPG when going from 5W30 to 10W30.

But as others mentioned, break in of a flat tappet engine needs special oil. Could care less about the weight, it is the additives that matter. There are now some special oils just for breaking in flat tappet cams, I think redline makes one. The standard recently has been Rotella diesel 15W40.