Thickest weight oil you used

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What was or is the thickest oil weight you guys have ever used in a vehicle? I think the thickest I used was Emblem 10w40 in my old 78' chevy truck I had.
 
I had an old Mitsubishi Mirage that lived a long hard life and had developed really loud lifters, I poured a bottle of STP in on top of the 3.5 qt sump of 10w40 Castrol GTX high mileage. Much better!
 
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20w-50 SuperTech in my 99' Neon R/T. Favorite car ive owned, didnt burn a drop of oil when i bought it. I seafoamed the intake manifold and gas a few months later, started burning oil. Would stall out on cold winter mornings with the 20w-50 before it came up to temp. 5w30 would burn a quart in 20 seconds at WOT.

It got so bad at one point i added some STP oil treatment on top of the 20w50 and my oil light came on when cold. Im guess it was too thick lol

The car was high mileage and had an abused life before i got it, so i think i killed it. Never again will i buy a modified car
 
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Valvoline Racing straight 50wt in my 1978 Dodge 1/2 ton 4x4, with a killer 318/2bbl.
Thought it was cool to bury oil pressure gauge.
Probably took 20HP to turn oil pump.
 
I used to use Valvoine 50wt in my 78 buick Regal with 231. It had a hardlife before I got it with with 118k miles on it back in 86. The low oil pressure light would come on at hot idle with 10w30 or 10w40. I remeber on cold Florida mornings before school I could hear the valves clatter for about 30 seconds before it would flow. Ran ok when I got rid of it with about 150k.

I probably wouldn't use anything heavier than 10 or 15w40.
 
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Straight 60 in my Harley. 15w-40 rotella in my 99 chev. It was before I discovered bitog. At least it was summertime. . That truck now has pyb 5w-30 in it. It's got over 260k on it and still starts first turn,just needs alot of front end cosmetics.
 
Right now I'm running 2 quarts of Mobil 1, 15w50 blended with 4 quarts of M1, EP, 5w20 for my winter run.

No problems for the winter....engine runs fine and the oil flows fast with the oversized K$N filter.

I picked up the oil summer in FL when they were clearing out the Kmart's.

At $3 a quart M1, 15w50, I cleared the shelves at a few stores.
 
20W50 in my 01 Toyota Tundra V8. Right when I bought the truck used I wanted to change the oil so why not use the stash for my 90's truck?

I might experiment with straight 50 in my 02 Chevy C1500 5.3L.
 
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