After reading some posts about this i've decided to go with Mobil 1 oil for my new engine. I'm just wondering what weight you guys would recommend using? It's for a 333 that will stay below the 6500rpm mark, even though it's balanced. I'll be changing the oil for the first time after the break in period. Since I used 5w-30 pennzoil for the break in, should I try and flush it out some with a quart or two of synthetic oil? Or is this unnecessary?

Thanks in advance

-Ben

Ben,
10w30 Mobil 1 should be fine. There is no reason to try and flush every drop of the Pennzoil out, it wont hurt a thing, the oils are all compatible.

Sounds good. Would 10w40 be too thick? I'm just paranoid about everything being oiled well after my last engine's problems. Thanks

I would and do run the 15-50. If you are running a flat tappet cam this is the Mobile 1 that is recommended. It still has all the additives that that the other ones don't. If the sunbirst emblem is on the bottle stating that it is for gasoline engines, it has a different additive package. This is from a Mobile 1 tech.

The recommended viscosity depends upon a lot of factors. In my opinion the biggest factor is the main and rod bearing clearances that were achieved when the engine was assembled. If the clearances are .001" then run 5w-30 or 10w-30. If the clearances are .003" then run 15w-50. The only difference in the 15w-50 Mobil one is that it does not contain the friction modifiers that would give it the EC (Energy Conserving) label. Not a big deal but the thinner grade Mobil One oils contain an additive that makes it more slippery.

Well I just filled it up with 10w 30 Mobil 1 before I check this post again. I can't believe I payed $25 for oil. lol I'm used to paying about $10 or so for the normal oil. But now I know everything will be lubricated as best as possible. graemlins/thumbsup.gif Thanks for the replies guys. I'm guessing the clearances were .001" given that the guy who built it put in 5w 30 for the break in period. But I could easily be wrong. Thanks for the replies guys....hopefully she keeps running cherry...whether or not I sell it.

By the way....anyone want to buy a 71 chevelle? ;) $7500, have $10,000 invested. Any takers?? smile.gif (seriously)

Actually, the problem as I understand it is energy oils do not contain Zinc and Phosphorus. These are mainly for wear protection (cams being effected the most)There is a push to eliminate these because the smog police think that they effect catalytic converters. This is why I have started to switch to Amsoil. I still use Mobil 1 in my wifes car or if I need a oil change and no Amsoil is available. Do a search on the web about Phosphorus and Zinc.

Thanks for the replies guys. Hopefully the 10W 30 Mobil 1 was the right stuff to use.

Digging up an old thread, but does Mobile 1 have enough Phosphorus and Zinc to be still good to use with (solid) flat tappet cams?

Thanks!!

Other factors besides bearing clearances to consider for choosing the correct viscosity would be the oil operating tempurature. Any oil will be thinner at 210F vs 170F. If you run a 160 thermostat, 170F oil is realistic. A 195 stat would probably net you 200F + temps. I run a 160 Stat, about .002 bearing clearnces and have never ran thicker than 0W-30 in my engine. Just think how much sooner at startup and how much more volume of oil (while the engine is running) reaches the critical lubricated parts, including the roller lifters vs lets say a 20w-50 vis oil.
BTW; this is year 6 for this engine.