Motor oil ?

Dave Castle

Dave Castle

Senior Member
Getting ready to fire up a used 59a engine in my 40 pickup. Everyone seems to have a opinion, what is the best motor oil to use ?
 
hope i dont start a war here, but detergent oil is a wonderful thing. keeps the motor clean, thats what we want. best situation is when its a new motor that is already clean! so, when you put detergent in a dirty motor its going to start cleaning like its supposed to. modern oils are made to "hold" the dirt so the filter can grab it. works good if you have a filter. if not, change it frequently for the first few hundred miles to get the now loose crud, that used to be stuck all over the place, outa there! the inside of most motor i have torn down is a nasty place. oil is cheap, flathead rebuilds are not. best wishes, skip
 
If your engine is so dirty you are leery of using Detergent oil, take the time to clean it out. Also mix any oil in an emergency.
 
Non detergent oil was more common back in the day and it was generally preferred for break in purposes but only for that initial 500 mile period. What ever you use just make sure and change it at that mileage for the first break in run. All the microscopic metal particles that are generated during that time frame will be purged and further bedding won't be nearly as aggressive as that first 500 mile period is. Flathead V8s don't have to worry much about ZDDP content. Only the later high compression motors of the late 50s thru the early 70s needed the 1200 PPM of ZDDP. Engines that are built up with high lift cams and high compression ratios need it also but most flat heads are built for mild street use.
 
Zinc additive is really not much of an issue with a flathead. The additives are required with high valve spring pressures found in OHV engines.
 
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If you are running standard spring valve pressures then I would recommend using a detergent straight 30 non synthetic oil for break-in and getting the rings to seat. I agree with others that say the zinc is not an issue unless you are running a modified engine. Then the zinc might have some merit depending on the mods.
 
Dave Castle said:
So it is not an issue to use a detergent oil in a flathead ?
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Yep - I do You just need to change more frequently -All the poisons are suspended in the oil and are discarded with it .

Synthetics are fine They are expensive and leak more as they offer better lubrication. I don't believe that they are cost effective given increased frequency of oil change in my non oil filtered car. As to mixing them with mineral oil it happens all the time either at manufacturer level or in your car when oil is topped up with a different oil to what's in it - I suspect it doesn't cause any problems.

Karl
 
The term detergent doesn't mean it cleans. It means that it keeps the sludge in suspension so that it is discarded with an oil change. Keeps the engine clean. Don't expect detergent oil to act like Tide in your engine!! Modern oils are WAAAAAY better than what was available back in the day. Use good quality multi-viscosity oil. I use 20W-50 and have great results - good oil pressure at all times.
 
doghair3 said:
Does anybody have an opinion on the oil Hemmings advertises for old classic cars?
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Yep. It's a rip-off. If you have a fresh engine, 10-30 will work great. If your engine is getting on in miles and years, you might want to try something a little thicker, say 20W-50. All oil is made to meet specifications. If is meets the spec, fine (I've never heard of any that doesn't).

These guys are just looking for people who will spend anything for something supposedly better. "There's one born every minute".
 
OP, have you at least pulled the oil pan and intake manifold to clean things up?

I've run everything from Wally World 10w30 dino oil, to Mobil1 10w30 full synthetic. No noticeable difference, but I was starting with a clean engine. I run for extended periods at highway speeds, so I use the Mobil1 lately. It can't hurt to have its benefits, and all of them leak the same :(
 
A little expensive but I use 10-30 synthetic. Had occasion to take apart an engine I had rebuilt that had a busted timing chain. The engine (not a Flatty) had 170,000 mi on it and I had run Mobil 1 in it from the first. Except for the timing chain gear that was the plastic over metal type (never to be used again) the engine looked new inside. Checked a few dimensions and all were still well within in tolerance. Been using full synthetic since. I don't find it leaks any worse ( IMO a wive's tail) with the Flatty than I've seen on other's.
 
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