What oil to use?

[Slick Steve]

Hi all!

What is the best oil to run in our beloved Flat 6's? Seems like I remember someone telling me 15w40, but I am not sure. I have a fair amount of Lucas 15w40 and Iwas hoping I could use it. If not what is best for these engines?

[BobT-47P15]

I use Valvoline 10w40. Seems to work just fine.

Additional opinions will be forthcoming, I'm sure.

[Young Ed]

I would think that weight would work fine. I run 10w40 in mine. 15w40 isn't that much thicker.

[Norm's Coupe]

Since they recommended 30 weight for summer months when the cars were new, I use 10W 30W.

[Dennis Hemingway]

I use 20w/50 in my 48 P15. With the temp during the summer here between 100-120 it runs at 35-40 psi oil presure.

Dennis:cool:

[Powerhouse]

I use plain 30 weight. Works fine...

[Tom Skinner]

I use Non-Detergent straight 30 Weight NAPA.

No problems.

Tom

[TodFitch]

I use 20w/50 in my 48 P15. With the temp during the summer here between 100-120 it runs at 35-40 psi oil presure.

Dennis:cool:

What he said. Actually I will also use 10w-30 if the store I am in doesn't happen to have 20w-50 in stock. The ambient temperatures don't get as hot here as where Dennis is but my engine does not have the full length water jacket (introduced in 1935) and I believe that means the oil will run at a higher temperature than in the later engines given the same driving conditions.

[grey beard]

My Favoirite Oil Rant . . . . . .

Some of you may be tired hearing my rant about oil, but I still stand by my guns . . . . . . actually, I've decided I'm gonna' do all my own thinking from now on, so I will always know I'm right!

Just kidding, there.

What you want to remember - and it's so easy to forget - is that our flathead engines weigh nearly TWICE as much as a bellybutton Chebby sbc's. This means that it takes much longer to get all that casting mass warmed up to operating temperatures. Especially for you folks what just putter around to shows and such, and never get 'em out on the highway and stretch their legs, it's possible to idle around town for an hour or more and still not have the oil up to full operating temperatures. Why, go buy a $19.95 Horrible Freight infra red touchless thermometer and check your own oil pan. You won't believe how long the dash temp gauge says normal before all the oil in the sump gets close to operating temps.

For this reason, I run a 180 degree stat in my 218, and it stays cool, even on long pulls. The proof of what I preach lies inside the valve chambers of many of our flatheads - in the from of sludge that is caused by condensation that cannot get out except by evaporation - that is, unless you have a PCV system, which is the very best thing for keeping crankcases and oil clean. Keep that nasty water out of your oil, and the oil will stay much cleaner and live a lot happier.

Wouldn't it be fun to have a group meet for all of us on this forum and while we're together, pull the lid on each valve cover, just for a look-see-squat-down-n-tell-the-trooth-moment of fun? I'll bet there'd be some red faces among us.

I am breaking my new engine in with Shell 20W50. I chose that specific oil based on the scientific and unalterable fact that it is what WalMart had on their shelf at the time. After a few hunnerd miles of break-in time, I will replace it with any good grade Diesel oil of the same or similar viscosity and grade.

We all know about the API oil ratings marked on containers. What we all may NOT know is that diesel oil still contains the zinc additives that have been removed from standard gasoline oils in the past several years. AND, because diesel combustion processes are different from gas engines - new diesel oil will turn pitch black in 100 miles - diesel lubicants have more detergent than gasoline oils. I personally believe that with our heavy casting blocks that warm up so slowly and have only part-time, by-pass oil filtration, this extra detergent will help keep our older engines cleaner, longer, better, gooder.

This comes from a personal friend who is an inorganic chemist for Valvoline (Ashland) Oil Company. AND, if you are one who lays awake at night worryin' about all this esoteric oil stuff, a top grade synthetic diesel multi-vis oil might be the crowning glory of all our flathead engines, what?

['37 P4 Touring]

I don't use multi-viscosity oil in my engine, I use Shell Rotella T straight 30 weight.

[1937 Dodge]

I use 5W-30 and run a 180 degree thermostat.

[austinsailor]

Far more important than the brand or weight is getting oil that has the proper amount of zinc in it.

In recent years they've removed most of the zinc additive. It's hell on our old cams.

Back when I was a kid in the 50's and 60's , it was common to have lobes wiped off of cams. In about 1960 or so, they added zinc additives to oil to solve this problem. For years you never heard of lobes being wiped off of cams. A couple years ago, they removed most of the zinc additives because it shortened the life of cat. converters. Now, lobes are disappearing again. I have a friend, for example, who just lost a lobe on his '74 Corvette he restored a couple years ago.

You can buy additives, expensive racing oils that have zinc or old oil made before zinc was removed.. You need a diesel oil with a rating of CI or earlier (CJ, I think, is the current and has little zinc. SE is current for spark engine oil and has little zinc. I bought a drum (55 gallons) of Rotella 30 weight CI to solve my problems for some years. Check with your local oil distributor - he may have some. Mine was $7 a gallon.

Do a search on zddp and you'll probably find enough info to explain it. This link has some info:

http://www.motorists.org/blog/warning-if-you-have-an-older-vehicle-choose-your-oil-carefully/

[radioguy7]

I use Non-Detergent straight 30 Weight NAPA.

No problems.

Tom

This is what I was recommended by an old Koot at a car show once when I first bought my 59 GMC truck. I figure he should know since he worked on them when they were new in 59. Made sense to me and I haven't had any issues since I've been using it. I bought the truck in 1995 and change the oil once a year but only put about 1800 miles a year on it on average.

[RobertKB]

20W50 in all my old flatties and my '63 Fairlane with 260 CID V8. I don't worry about zinc content as a lot of studies and posts on this forum don't agree that you need zinc. A lot of the problem is being blamed on lower quality replacement parts. I think anything you put in them is 5 times better than what they got new.

[Plymouthy Adams]

zinc is primary a necessity in break in...afterwards..you can go to symthetic if you choose...

[Norm's Coupe]

Like grey beard, I run a 180 thermostat too. My oil stays nice and clean and doesn't have any moisture in it when I check it.

As for grey beard's comment about pulling each others valve covers at a meet. Well..........that would not happen on my coupe. They don't get pulled unless it's to work on the valves. That way I don't have to keep installing new gaskets. So.......people would just have to use their imagination as to how my valve chamber looked.

[TodFitch]

Like grey beard' date=' I run a 180 thermostat too. My oil stays nice and clean and doesn't have any moisture in it when I check it.

As for grey beard's comment about pulling each others valve covers at a meet. Well..........that would not happen on my coupe. They don't get pulled unless it's to work on the valves. That way I don't have to keep installing new gaskets. So.......people would just have to use their imagination as to how my valve chamber looked.[/quote']

Could this type of contest create a market for Lexan valve covers?

[WatchingWolf]

Could this type of contest create a market for Lexan valve covers?

Years ago, I spent a couple years at a tech school to get a pc. of paper that said I was allowed to get greasy. We had a 318 in a building and grounds truck / gunnie pig vehicle with some sort of clear valve covers so you could see stuff working. I think they may have vac formed them themselves. Seems to me they leaked a lot too.

[Niel Hoback]

I use 10w30 or 10w40 that has spent about 3000 miles in my Buick. I never change the oil in the Plymouth because it burns and leaks so much that I just keep adding to it.

Not to worry, I never let it get much lower than a quart low.

[grey beard]

Had an uncle - Melvin - who was a trucker, back in the day. Drove a tired old GMC long nose with a 318 cabbage slicer two-cycle Detroit Diesel. Between all the oil leaks and all the blow-by, he never changed oil in it. Just kept adding oil every time he filled up with fuel. Changed the Luberfiner filter behind the cab once a year whether it needed it or not. Of course, diesel oil always is black, even when you change it regularly, so it always looked the same to him. Go figger . . . . . .

Q: What's wrong when a Detroit Diesel doesn't leak oil?

A: It's out of oil!

[greg g]

been running 15w-40 Traveller Diesel oil from Tractor Supply Company 8.99 a gallon, 15 and change for a 2 gal. for 3 years now. Yes it does blacken up quick but seems to be working quite well. Still holding the same oil pressure as when the rebuild was done. I read on a site somewhee that there was too much detergent in diesel oil, but in a clean nearly new engine what might the problem be? Lable says for use in all Diesel and gasoline engines.

[Don Coatney]

Had an uncle - Melvin - who was a trucker, back in the day. Drove a tired old GMC long nose with a 318 cabbage slicer two-cycle Detroit Diesel. Between all the oil leaks and all the blow-by, he never changed oil in it. Just kept adding oil every time he filled up with fuel. Changed the Luberfiner filter behind the cab once a year whether it needed it or not. Of course, diesel oil always is black, even when you change it regularly, so it always looked the same to him. Go figger . . . . . .

Q: What's wrong when a Detroit Diesel doesn't leak oil?

A: It's out of oil!

Dave;

I once owned a Detroit 6V53 two stroke supercharged diesel engine. It did not leak oil any more than my flathead engine does. The recommended oil change interval for this engine was 50,000 miles if my memory serves me correctly. Oil pan capacity was around 20 quarts. These two stroke diesels have a red line around 3500 RPM's. A bit high for most conventional diesels as thy normally are red lined around 1800 RPM's.

[Brendan D25]

Ahh the memories, the "screamin jimmy"! That's what I started out on in the seventies, with two sticks. Later moved up to a V12 with 13 over, and a sleeper, didn't have to sleep on a piece of plywood anymore.

[Merle Coggins]

I once replaced a blower on a 6V53 in a crane. After resetting the governor, valves and injectors I rechecked the HFI (High Free Idle). It was right on spec at 3800 RPM They really scream.

A former co-worker used to call them "Convertor Engines" because they convert fuel into noise.

Merle