Silverstreak36 Posted September 6, 2021 Share Posted September 6, 2021 The question of the day, my 1936 Pontiac deluxe carries a 1954 flathead 6 motor. What type of oil should I use in this vehicle when doing oil changes? Link to comment Share on other sites More sharing options...
JFranklin Posted September 6, 2021 Share Posted September 6, 2021 If the engine is clean buy some good 10-30 oil and enjoy driving your car. If you don't know if the engine is clean, drop the pan and clean it and inspect the engine condition, then use a good 10-30 oil. 1 Link to comment Share on other sites More sharing options...
PONTIAC1953 Posted September 8, 2021 Share Posted September 8, 2021 pontiac said straight 30 weight in warm weather, straight 20 weight in cold weather. Link to comment Share on other sites More sharing options...
JFranklin Posted September 8, 2021 Share Posted September 8, 2021 1 hour ago, pontiac1953 said: pontiac said straight 30 weight in warm weather, straight 20 weight in cold weather. Many manufacturers made this same recommendation, but multi-weight oil wasn't available or in wide use if available back then. 1 Link to comment Share on other sites More sharing options...
PONTIAC1953 Posted September 11, 2021 Share Posted September 11, 2021 On 9/8/2021 at 1:19 PM, JFranklin said: Many manufacturers made this same recommendation, but multi-weight oil wasn't available or in wide use if available back then. well multi grade motor oils are rated that they behave like the higher weight under controlled lab conditions, such as 10-30 or 15-40, not the same conditions in real life driving, granted the motor oils today have far better anti wear and detergent additives vs the single weight oils 70 plus years ago. Pontiac straight 8 and straight 6 are rugged, low rpm engines with solid lifters and full pressure lubrication, i stand by what Pontiac recommended then has for what oil weight to use in their engines. Link to comment Share on other sites More sharing options...
JFranklin Posted September 11, 2021 Share Posted September 11, 2021 (edited) When I was a kid I saw a display in the Los Angeles Museum of Science of single vs Muti-weight oil. Four 8 foot clear tubes on a teeter totter type device that held a tennis ball size steel ball in oil. 30 weight cold, 30 hot, 10-30 cold and 10-30 hot. You could see the ball fall through the oils and make a comparison. I use multi weight oil. Edited September 11, 2021 by JFranklin (see edit history) Link to comment Share on other sites More sharing options...
Summershandy Posted September 29, 2021 Share Posted September 29, 2021 I've ran 15-40 for a couple years summer only but in all fairness it's in need of a rebuild. It smokes when cold and lessens once driven. Keeps the pressure where I like it. Link to comment Share on other sites More sharing options...
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