oil

[rotorwrench]

SAE 50 and 60 oils are for air cooled engines that run at higher average temperatures than liquid cooled engines which also use oil coolers. The average liquid cooled engine will survive on about anything from SAE 20W/20 to SAE 40. The modern thin oils less than SAE 20 are designed for better windage in engines that have very tight tolerances so that they will get better mileage (although only slightly better).

The model A engine can get pretty loose tolerances over a long period of wear & tear and it has relatively large bores for a 4-cylinder. It also has a very antiquated oiling system. Higher viscosities might help with film build but they may not help with warm up at all. A lot of wear happens at warm up until the flow gets going well. A person should get to know a shop that does good babbitt work to fix those loose bearings so a return to the lower viscosities will be of value.

Use what ever oil you feel comfortable with but all around averages point toward 20W/20 for cold weather and 30 for warm. Multi-vis oils are only as good as the polymers that are used. These break down rather quickly so oil changes should be frequent if using 10W/30 or the like. 20W/50 would be good for a very loose and worn engine but even that polymer breaks down quickly. I experienced a lot of engine bearing failures in the helicopter engines using 20W/50 multi-vis. I've not used anything but straight grade SAE 50 since that became apparent for hot weather in Texas. These engines run a lot hotter than any car ever would so there is no real comparison. They run two oil coolers on the average.

As far as ZDDP is concerned, a model A can survive without any at all but the amount in modern multi-vis oil is fine. These engines have large area flat tappet followers and low pressure valve springs so it is overkill to use any more the 800 PPM oil. 1200 PPM oil is for high performance cams and heavy valve spring pressures. More than 1200 PPM is detrimental to the engine. The stuff is caustic so more is NOT better.

[Mulletwagon]

Originally Posted by 1929

I just use what my rebuilder said to use-Rotella 15W-40 with one bottle ZDDP

Same here. A gallon jug plus STP that includes ZDDP brings the level right up to the dip stick full line.

[Purdy Swoft]

I've been using Walmart 20w50 for years with good results .

[Mike V. Florida]

Originally Posted by California Travieso

Bobsmanstuff,

From the endless posts on the subject, we can summarize: whatever weight, type, e.g., detergent or non-detergent, single viscosity or multi-viscosity, and the brand you prefer, in accordance with season and what your pocket book can afford.

Change it as often as you like, 500 miles, 1,000 miles, 5,000 miles or once a year if you don't drive much. Some like change it before winter and before summer.

Some guys like Shell Rotella Diesel Oil, 10/40 or 15/40. Others buy whatever is on sale.

Some guy even stated he uses the oil he drains from his modern car. In that case, it would probably be wise to install a filter!

David Serrano

Could not agree more!!!!!