BEST ENGINE OIL FOR A SLANT SIX ?

[Guest erp52]

I have a 1961 Dodge Lancer with the 225 slant engine.  What engine oil shouldd I use? Car has 130,000 miles.  Ed

[Fleek]

I have had several over the years. Great engines. I always used a good brand of 30 weight oil. If you want a multi weight then 10w30 would be good. 

[crazycars]

I'd recommend 20W-50. Had slant sixes for years. Love them.

 

[fraso]

There is no need to use anything heavier than a 10W-30 engine oil.  With a stock slant six valve train, the 800 ppm maximum phosphorus content of an API CK-4/SN Heavy Duty Engine Oil should be adequate although Widman recommends higher phosphorus levels for flat tappet engines (see Corvair Oil Article).

 

As for a 20W-50 grade, this is way too thick and not recommended by Chrysler for slant sixes in 1964/65 and likely not in 1961.  The heaviest recommended in my 1965 owner's manual was 20W-40 for temperatures consistently above freezing so a 15W-40 would also be suitable.

 

See Engine Wear.