oil question

[Jack Garman]

What brand of oil and what weight is best for a 40 flathead 74 ?

[Rollo]

Jack,
I use HD 60 wt in all my antique HD's and get it from the HD shop. Others here will advise you differently. Their choice. I do this beceause HD spends millions of dollars testing and formulaing their oils specifically for use in their engines and so they are not going to sell something that isn't inteneded for this use. One bottom line thing I think all can agree on is use good quality oil and make sure it is for use in air cooled engines. The API rating. Like I say others have differing opinions but this is what has worked for me for about 40 years so I stick with it. I use Valvoline 50 wt in my Indian.

Tom (Rollo) Hardy
AMCA #12766

[sirhrmechanic]

^^^^ This.

And change it often. Oil is cheap. Engines are expensive. If you live somewhere where you store your bike for the winter, the BEST thing you can do for it is change the oil before you put it away. Get rid of oil that has combustion by-products and nastiness in it.

With antiques in particular, mileage is virtually a non-entity when it comes to oil. Time, on the other hand, is your enemy. At least once a year, change that oil. And if you store, make your annual change when you put it away, not when you get it out.

Cheers,

Sirhr

[T. Cotten]

Folks,

Valvoline VR1 has ZDDP in it, which is rare since it messes with catalytic converters.

And Tom!

An associate of mine was told by a lubricants distributor that at the time, H-D's oil was produced by Mystik, the same as some farm supply retailers offer, such as Farm&Fleet.

Do you really believe H-D would spend millions on testing oil?

....Cotten

[downunder vl]

Someone on a previous thread recommended Shell Aero W120 SAE 60 so I thought that I would give it a try in my VL flathead. It's made for use in aviation piston engines and comes in SAE 40 and SAE 50 also. In our climate I ran 1 tank of Harley SAE 60 and then ran a tank of Shell. As SIRHRMECHANIC says oil is cheap insurance and because a VL runs with about 150 mls of oil in the sump I change the oil after every decent run. It's so easy with a VL. As soon as I stop the engine I get my drip tray, push down the lever, lock it in place and give it a few minutes. If there's 150 mls plus or minus a few mls it's a great check that everyting is doing what it's supposed to. When I compared the two oils I found that the Shell was much more viscous when it came out hot than the HD which came out like water. I also found that when I had the heads off that there was less carbon built up. I assume that a 40 flathead runs similarly as hot as a VL so I would give the Shell a try. In Australia I get it from one of the local airfields where it's readily available and as a bonus it's less expensive than HD. Price doesn't really matter but I'm happier paying less for an oil that I think is doing a better job.

[Sargehere]

For a hot climate, like Flarr-dah, here, my routine for Old Harley engines is Harley 60 weight in the Summer and 50 weight in the Winter. That's the only item I buy in Harley dealerships that fits my old (1937 UL) Harley. In Virginia, I'd probably run Harley 50 weight all-year-round. 60 weight tends to act like molasses in cold engines, making them hard to start in the winter.

If it doesn't get up in the 90s all the time in the Summer where you live, 50 weight all year round is fine. That's what the engine was designed for: Straight, single-grade Harley oil designed for air-cooled engines. I've never had a problem. related to oil.

[sirhrmechanic]

Cotten brings up a big issue these days and that is ZDDP. Working with antique cars on a daily basis, I can say that it is a real issue and a real concern.

ZDDP was removed from most oil (heading towards all oil) a few years ago because it degrades emissions controls and probably because Al Gore doesn't like it. For certain engines, it is very important to put-back a ZDDP additive or damage can result...

What the ZDDP helps with is high-pressure metal-on-metal areas in an engine... particularly flat tappets/cam followers. Engines with roller tappets are much less prone to any damage without ZDDP. In our world, mainly prewar British, virtually every car used roller tappets all the way back to 1904. The exception was the Phantom 2 and some of the PIII conversion that went with a non-roller cam follower. Without ZDDP, these engines suffer appalling damage in a remarkably short amount of time. Similarly, the postwar B-series sixes and V8's used flat, non-roller cam followers and are very prone to damage if ZDDP additive is not used. Model T and Model A users also need to use a ZDDP additive or oil.

I have read but not experienced directly that the postwar Jaguar engines have been suffering badly w.out ZDDP (or at least did until people recognized the problems) and that musclecar motors with high-strung V8's are very suceptible to cam and cam-follower damage.

All that said... you need to know your vehicle and the recommendations of your manufacturer (or club experts.) Many vintage motorcycles use roller cam followers. With these, you have no problem w. oil that lacks ZDDP. But not *all* bikes. Learn what you have, find out what should be run. Harley may or may not spend millions researching oil, as was pointed out above... but somebody did. And HD would not recommend it and put their label on it if they weren't putting their reputation on the line. So find out what you should be running.

Finally, there are a number of good ZDDP additives out there. We run the one sold by Langs Model T parts in Winchenden, Ma. in engines that have flat tappets. Keep in mind, though, that mixing instructions need to be followed. ZDDP in small concentrations does what it is supposed to with high-pressure metal-on-metal areas. In too high a concentration, it rapidly attacks yellow-metals and will cause a fast breakdown and destruction of any bronze bushings, bearing surfaces, ball cages, etc. Definitely a case of too much NOT being a good thing.

There have been some really indepth treatises on ZDDP written for the old car world. The best probably by Bill Kennedy of the SGA. His research was done in conjunction with a research chemist and resulted in a two-part additive "SGA1 and SGA2" that is recommended for early British cars (pre-1930.). But is very expensive. His work developing the chemistry, though, was extremely detailed.

Again, best bet is to use a good oil... use a recommended oil... and know your engine and what, specifically, it needs. Then change it all the time.

Cheers,

Sirhr

[Sargehere]

And, back to Jack Garman's original question (post #1): a 1940 U-model Flathead Harley has roller-bearing mains and roller tappets, not the alternative. Absent a supply of Harley straight 50 and 60 (if I didn't live near a dealership) I used Valvoline Aero oil before and it's perfectly good in our engines.

That's also formulated for air-cooled piston engines that run run up many hours at (boringly) steady rpm's, and is just fine in roller-bearing Harley engines. Just change oil frequently and keep the tank full, and you won't have any problem related to oil.