Most older engines don't hold synthetic oil very well. If every joint is freshly sealed with new high tech glue stuff we have now, it'll (probably) be fine.
Try it You may like it It won't hurt anything I run it in my model A and my son runs it his I swear by it and run it in everything all the way down to my weed ripper Sent from my iPhone using Tapatalk
Just don't show the can it comes in to the motor,Itll never know the difference....Duhhhhhhhhhhh besides the motor cant read...Its all in YOUR head
I would stick with 15-40 diesel grade. Has worked for me for the last 75000 miles. There is a theory that synthetic does not stick to the cam in flat tappet engines, thus causing premature cam ware. Have not had any experience with synthetic oil, so not sure of the validity of the above theory. Keep in mind that flatheads are 1930's technology and run greater clearances than modern engines. Just my 2 cents worth!!!!! Besides 15-40 is about 1/3 the price of synthetic
I am running Mobil 1 15-50 in my '51 club coupe and it works fine. I had a bunch left over from my Hemi-powered dirt track car, so I decided not to waste it. Another advantage is that it has 1300 PPM zinc. 10-30W Mobil 1 has only 800. Not that it makes any difference in a flathead with our low valve spring pressures.
That is not a theory, it is a hypothesis. Hypothesis vs. Theory: A hypothesis is either a suggested explanation for an observable phenomenon, or a reasoned prediction of a possible causal correlation among multiple phenomena. In science, a theory is a tested, well-substantiated, unifying explanation for a set of verified, proven factors. Correlation (if there is any) does not equal causation. I see an overwhelming number of umbrellas when it is is raining, and almost none when the sun is out. I therefore hypothesize that umbrellas cause rain.
The key here is the weight of the oil, not it's use (diesel oil). Every oil I have researched that has "/50" in it's name has had at least 1000 ppm zinc and phosphorus. I don't think this same statement can be made for those that have "Diesel" in the name. If someone can come up with an oil for which this is not true, let me know. I can't find one.
First off, I am an independent Amsoil dealer, and have been so for about 20 years. And I use it in every internal combustion engined apparatus I own/operate. But the only flatheads I own are on a lawnmower and a generator. Synthetics can be and are blended in all sorts of specialized oils and that's one of their main values over petro oils. with petro, you must remove that which you don't want and hope you kept the desirable qualities. The varnishes, sludge, and tars that are inevitable with many petro based oils aren't there in a good synthetic. But most synthetics are by nature very powerful cleansing agents, and if an old flathead, or any other engine which has been subjected to neglecting to change oil regularly, or in the old running around town with no thermostats "to keep it cool", etc. then it's going to have sludge and varnishes that tend to seal up potential leaks that would have leaked with conventional oil if the engine had been cared for with regular oil changes, proper operating temps, etc. So, while as I said the only flatheads I've run synthetic in are on lawnmowers and generators, there's no reason they shouldn't be used in a clean, good condition engine. But I wouldn't take Uncle Herny's old F1 farm truck that been out in the barn most of the time except to once in awhile haul a bale of hay to the back pastuire (after you use booster cables because the battery was dead) to the back pasture, and change it to synthetic oil.
The Jalopy Journal
