Multipurpose oil question

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Mar 16, 2004
I have been searching this board for a while and the amount of good information is overwhelming. The more I learn, the less I seem to know. I have a question about the best commonly available oil (Redline, Amsoil, and Royal Purple aren't) for a dual purpose car. It is a SBC with 150 nitrous shot that does spend some time on the street. Max rpm is 7000, cruise rpm is 3000 at 55. Horsepower using several calculators is around 500 motor and 670 on nitrous. Used for drag racing on weekends. Currently I run Castrol 20W-50 which is a pretty good conventional oil from what I have read here. I tried Mobil 1 in the past and had constant problems with AC Delco filters leaking. Went back to heavier weight conventional because I read somewhere that a heavier oil tends to have a cushioning effect on the bearings under extreme load and all I could find in Mobil was 10W-30. I am mainly looking for the maximum protection for roller lifters and bearings and not necessairly for the absolute last horsepower like a thinner oil would give. I am worried about a straight 50 weight because I do drive the car on the street some in the winter even though I do let it warm up some and keep rpm's low (around 2000) for the first 10 miles or so. But on the straight weights side I have read an article (years ago) that said a straight weight was better because the viscocity modifiers added to make multi-vis offer no lubrication qualities. I think the Rotella oils would be pretty good in my application due to the environment they were designed for but am worried about the extremely high detergent package. Sorry for the long post, I am confused about the little bit of knowledge I have on the oil subject (which could be all wrong). One fun thing though, the oil filter knowledge I gained here let me prove a Chevrolet parts man wrong, he couldn't believe the lowly SuperTech's were made by the same company as his beloved Duraguard Silver $5.99 filters. So I cut them both open and brought them to him. Then he got quiet and wouldn't talk to me anymore. Great fun. Thanks, Clay
Well conventional wisdom is that heavier oil gives more cushioning effect but we have seen some of the best bearing wear from the 0W-30 German Castrol and even the 0W-20 Motorcraft and other 20 wt oils. I'd play safe though and stick with no lighter than a 40 wt oil. You could go with say a 50/50 mixture of M-1 10W-30 and 15W-50 oil. Of course there is Delvac 5W-40 but that's hard to come by. Amsoil is available at lots of places.

Perhaps someone with more experience with the Small Block Chevies will chime in. Which engine do you have??

Why not get redline 10w40 or one of their racing oils from (site sponsor)
I ordered from them and they ship fast. They were offering 10% off their low prices (low compared to summitracing anyway)
D4 atf was 6.30/qt there and its 10$ at summit
Their shipping on 17qt's was under 10$ 8.xx If I remember right.

Oh fyi the redline race oils contain no detergents... so you might want the regular oil...

From my oil shops website
Red Line 15W50 & 20W50:

The ultimate high-temperature protection in Red Line engine oils recommended for street use. Good for engines that regularly run very high oil temperatures. Best for engines that run large clearances such as air-cooled engines or large-displacement, all-out racing engines that see occasional street use. Provides 25% more viscosity in bearings than petroleum 20W-50s. Not recommended for use in cold climates where temperatures are at or below 10°F or -12°C. Not recommended for street use in production engines that see sustained oil temperatures below 225°F. Those engines should use Red Line 10W-30 or 10W-40.

Red Line 10W40:

Best choice for engines that typically run high oil temperature. Best choice for engines in daily drivers operated in very hot weather on a regular basis. Best choice for medium and heavy duty gasoline engines in trucks. Best choice for high-performance engines that see street as well as frequent racetrack duty. Thicker oil film at operating temperature than a petro-based 20W-50.

I'm not sure how much that helps you but I had a very good experience with that vendor...

Originally posted by nuity:
I have a question about the best commonly available oil (Redline, Amsoil, and Royal Purple aren't)

As Rand already said but I'll reinforce--Red Line is highly available and convenient. All you have to do is open your door when the UPS guy delivers it.

I'd use RL 10W-40. EXCELLENT oil with NO viscosity-index improvers.
Since your spraying a heavy shot of nitrous I would go with a Synthetic 50W oil. Nitrous builds extreme heat inside an engine. I used to spray my 355CI boat engine with a 150 Wet Shot and after 10 seconds of spraying my oil temp would rise from 200 degrees to 280+ and take a good half hour of cruising to drop down to normal range. Mind you this increase in oil temperature happended within 10 seconds!!!!

My reccomendations would be

Mobil1 15W-50 commonly available at Wallmart.
Amsoil 20W-50 or a comparable weight from Redline or Royal Purple.
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