Mobil 1 0w40, change it once a year.

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2016 Corvette Stingray 2LT
1969 280SE
2023 Ram 1500
2007 Tiara 3200

I used to put only Mobil 1 0-w-40 in my m119 4.2, till one day i heard rod knock as I was starting the engine (over 40c ambient temperature at the time).

Since then I've been using 20-w-50.

I tried Mobil 1 synthetic one time. My lifters were noisy as hell! I went back to my tried and true Castrol 20-50, and all was better. Ive been using it for the last 100K religiously, and no problems. I run 10-30 in the winter time, however.

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93 300D 2.5 Turbo, Black/Palomino 273K
09 E350 Black/Black 41K

I agree. M1 is the way to go.

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"I have no convictions ... I blow with the wind, and the prevailing wind happens to be from Vichy"

Current
Monika '74 450 SL
BrownHilda '79 280SL
FoxyCleopatra '99 Chevy Suburban
Scarlett 2014 Jeep Cherokee
Krystal 2004 Volvo S60
Gone
'74 Jeep CJ5
'97 Jeep ZJ Laredo
Rudolf ‘86 300SDL
Bruno '81 300SD
Fritzi '84 BMW
'92 Subaru
'96 Impala SS
'71 Buick GS conv
'67 GTO conv
'63 Corvair conv
'57 Nomad