Your favorite motor oil for Buick/Olds/Rover aluminum v8?

[Moderator]

I'm curious to know what you guys are using, and why.



For my carbureted Buick 215, I used conventional Castrol 20w-50 until switching to Valvoline VR-1 20w-50 (conventional) racing oil just a couple years ago to get a (presumably) higher ZDDP level on the assumption my flat tappet camshaft might benefit. In either case, I changed oil rather frequently (at least in terms of miles). Engine internals appeared spotless when I upgraded cylinder heads a couple years ago. ~35,000 miles since rebuild. Plenty of oil pressure. No significant oil consumption, though my rear main seal has always leaked. Plenty of cooling capacity. Functional PCV system.

Now, I have EFI installed, and I'm considering trying a synthetic oil. I figure I might try a longer oil change interval since presumably less gasoline is contaminating my oil at start-up. Maybe I'll change my oil every two or three years instead of once a year whether it needs it or not;)  Also, I wonder if thinner viscosity oil might give me noticeably better fuel economy.

Your thoughts?

[MG four six eight]

Curtis,

Oil threads seem to turn in to a hotly debated item on most forums! But for what it's worth I use Mobil 1 10w30, although I do break the engine in on conventional oil first.
Mainly I use it because I've always had good luck with Mobil 1 in my daily driver's that are now approaching 200k on the odometer. Normally I will pick it up on sale at Costco for $10 off per case.

I your bearing clearances are good, then you should be able to use a thinner weight oil for a possible increase in fuel economy and power. Modern engines use thinner oil for that very reason.

I still change my oil at 3500 - 4000 miles though. I'm not a big believer in extended oil changes.With every engine that I've torn down at work for premature wear , it's always been the same story. The owner didn't change they're oil often enough.

Bill

[ex-tyke]

Been using 10W30 synthetic in my Ford engine for a number of years now - no particular brand but usually Mobil 1 or Castrol Syntec. Hard to say if there are any performance/engine benefits but it allows the extended oil change interval to one drving season.
 Oil & filter get changed every Winter before the next driving season.

[roverman]

Not in a RV8-but, I've been having good results with Valvolene synthetic blend/hi mileage.Good price at Wally,.  FWIW, roverman.

[MGBV8]

I used to believe in Mobil 1. Until I found out Exxon/ Mobil switched most of their product it to dino base stock  (group III vs group IV) like Castol after they lost the lawsuit. If you are going to run synthetic use Amsoil.

In the 90s, Mobil filed suit against Castrol for falsely advertising Syntec oil as synthetic, when in fact it contained a Group III, highly hydroprocessed mineral (Dino) oil, instead of a chemically synthesized (group IV or V) basestock. Due to the amount that the mineral oil had been chemically changed, the judge decided in Castrol's favor. As a result, any oil containing this highly hydroprocessed mineral (Dino) oil (currently called Group III basestock by the American Petroleum Institute) can be marketed as a synthetic oil. Since the original synthetic basestock (polyalphaolefin or PAO) is much more expensive than the Group III basestock, most of the oil blenders switched to the Group III basestock, which significantly increased their profit margins.

[mgb260]

I'm with Art, Valvoline synthetic blend High Mileage 10/40 in my 190,000 mile F150. Don't have a Buick/Rover at this time but, if I did I would use it. I would put a bottle of STP(or Zinc additive) in every oil change  in a flat cam motor.

[kstevusa]

Guess I'm in minority, I change my oil and filter every 5,000 miles and utilize Shell 4000 5/30w. Dino Oil.  This was OEM spec in the 93 Mustang and engine is approaching 160,000 miles. It was clean under the intake and valve covers 2 years ago. Oil pressure is good also.  My mileage is only 40,000 since the conversion, but no oil consumption.  If not its broken, I do not intend to attempt to fix.

[mgb260]

Pennzoil's new Platinum is full synthetic, actually made from natural gas. Haven't researched it though.

[hoffbug]

Crower is recommending http://zddplus.com/ by name for all of its flat tappet cams.. Ill probably run Brad Penn with ZZDP plus in the little Olds engine.

[BlownMGB-V8]

I've heard recommendations that you thoroughly mix the bottle of zddp with a quart of oil before pouring it in the engine.

Jim