Originally Posted By: BrocLuno
If you are an actual motor person. One who either specs custom built engines, or builds your own for a performance application and then drives and maintains that application; what oil do you run and why?
I build moderately old school American V-8's for fun cars, mostly on the street. I've been doing this on and off for about 5 decades. I break in those engines on Chevron Supreme 10W-40. I change oil & filter at 100 miles and again at 500. Then I run yearly OCI's as most of these cars and trucks do not get 7,500 a year.
I have used Delo400 as my go-to oil for decades for general use and that includes a type of engine I build that I call a drooler. That is it has extra internal oiling points and runs a HV pump with the lowest pressure spring I can install so that it max's at ~50 psi.
When I was young and did not know better, I swore oil pressure was important so I wasted power driving high pressure systems and the associated wear on distributor gears and broken oil pump drives. At some point the light went on and I quit doing that ...
So my oils are Chevron Supreme and Delo400. I am adding Valvoline MaxLife as a third oil...
So how bout you'all ???
Here is my information:
High school car - 1968 Buick GS400 bought it with 43k on it. Oil light would flicker on at hot idle with xw30 oils so I stepped up to 10w40. Nylon timing gear wore out at about 80k. A very good older mechanic mentor friend said I should stay away from thick oils for this reason (timing gears / distributor gear wear etc.). Faced with a catch 22 I rebuilt the engine (over the counter Stage 1 and 2 parts) and used Castrol GTX 5w30 the rest of the car's life (114k). I have followed his advice to this day, using the thinnest oil safely possible.
Next car 1970 Judge RAIV (real Judge, real RAIV not a clone) - I struggled enormously with this car for the first 1-2 years I owned it after rebuilding the worn out engine. The lifters I used restricted oil to the top of the engine (via the usual lifter / pushrod / rocker path). I observed this after assembly, checked the usual suspect missing rear oil galley plug but that was ok. The consequence of the poor oil flow up top was I would burn rocker balls out after sustained high RPM which was pretty much any highway driving in a 3.90:1 geared car. I switched from the generic 10w40 I was using to 30 Valvoline VR1. This did not solve my problem but that oil, without question, allowed the rocker balls to last the longest and made me a fan of VR1 ever after. I eventually went to roller rockers and later on at some point after a cam and lifter change (I experimented lots with that car) the oil issue vanished. It was simply either a poor lifter set or wrong part (many manufacturers just use Chevy .842 lifters in Pontiacs, maybe these were the restricted orifice ones? Anyway...). I settled into either my VR1 (if on sale) or any brand 10w40 or Rotella 15w40, 30 and 10w40 grades were called for the RAIV due to increased bearing clearances over a normal production engine.
Now car 1970 LS6 Chevelle - The born with engine is popped out and sits in the corner of my shop ready to swap back in case of a sale. I have a mid-80's bought brand new GM crate XCH LS7 in the car now. I use pretty much use anything (xw30) in that engine, it is the most trouble free performance engine I have had and the least fussy on oil requirements. Currently using 10w30 T5. I have an aftermarket SW oil gauge (previous owner put it in, the car is an idiot light car and will be again shortly as I am taking the gauges out and returning the car to the born with configuration) and it shows 70psi cold start, 40psi hot idle, 65-65psi hot highway. Those numbers are more than fine.
Vacation car 2011 Shelby GT500 - I didn't build this engine, Ford did at their Romeo plant, it is the highest HP / most powerful car I have ever owned so it counts as "built" I believe. Factory calls for 5w50 and it killed me to use that grade oil but I did for the first few years. I have switched to M1 0w40 now. I won't go lower in hot viscosity number and I do have some 5w50 and 15w50 in my stash which I will use in this car. The 50 is for track / hard use which I don't see with the car and I am zen with the lighter 40, especially with a superior quality M1. I will say this about the car and why the oil called for is a 5w50... that oil gets scorching hot, even under normal driving. I cannot touch the oil filter with my bare hands during the oil change and if I get accidentally splashed by draining oil it gives me a visible bad burn. I measured the oil filter can temp at idle and it was 220F... my daily driver GMC is about 180F. Whatever is going on inside that motor (oil cooling the pistons, the supercharger, whatever) that oil runs very hot.
Additional notes: 1) I have noticed universally increased oil consumption with the lighter oils (xw30 vs. xw40/50) in old muscle cars. That seems to be the only trade off with my penchant for light oil. 2) I have experimented (gasp!) with 5w20 in my newer GM daily driver vehicles that spec 5w30 and observed no ill effects. I took my 2004 Pontiac Grand Prix on vacation with 5w20 in the hot summer months to the Wenatchee Valley in Washington on the way to Seattle. 100+F ambient, AC on, high speed interstate driving, steep grades all on 5w20. I also observed no benefit either i.e. increased economy 3) If I used synthetic in my old muscle cars, which I don't due to wasteful cost i.e. cost with no benefit, I would use a 0w30.