JoeW: 3/15/2000 - 9:37:50 AM
Oil brand & weight
I recently purchased a 41 Ford with a V-8, that has 73,000 miles, runs great, does not burn oil, and has good oil pressure. It's time to change oil, and I wondered what oil would be the best choice for this engine. A friend recommended Valvoline 10W30, but I'm hesitant to use that. Ford says 10W, 20W, or 30W depending on temperature. I would like to know what an experienced Flathead owner recommends. THANKS!

JWL: 3/15/2000 - 10:22:51 AM
RE: Oil brand & weight
I live in a warm climate and use Valvoline 20-50 thruout the year. If I lived in a cold climate I would use 10-40 in the winter and 20-50 in the summer.

Paul Selfe: 3/15/2000 - 12:06:34 PM
RE: Oil brand & weight
Running 10W30 or synthetic oil in a flathead is fine, if the engine is clean to start with, and you have a good filtration system. A motor with 73K. on it will probably have some sludge in it, that can break loose and plug up vital oil passages, leading to early failure. Run some kerosene thru it (carefully) and clean out the oil pan first.

mr bill: 3/15/2000 - 3:14:48 PM
RE: Oil brand & weight
10W, 20W, 30W???? Any info I have ever seen calls for 40W. Most call for straight weight but I have seen some that say you can use multi-weight.

JoeW: 3/15/2000 - 7:02:39 PM
RE: Oil brand & weight
I got the oil weight specs from the 41 owners manual. Also I neglected to mention that I don't have an oil filter on this car.

Russ: 3/15/2000 - 10:34:56 PM
RE: Oil brand & weight
I'm with JWL, I always use 20w/50. If the car's been running, no doubt it's been running detergent oil so that's not an issue. I like the multi-weight properties. Todays oils hold impurities in suspension very well, so without the filter, change it when it looks like it needs it. Or you could go overboard like I do and change it every 1000 miles. As to the '41 spec of 40w, that was when multiweights didn't exist, and the quality of oils was very primitive compared to today's.

51al: 3/16/2000 - 6:20:30 AM
RE: Oil brand & weight
There are as many oils on the market as carters got pills i argee with jwl here in the south 20w 50 is just fine. if the weather is cold you will need a lower viscosty weight such as 10w 40 and if you are 6volts even more.most all oil oil is detegent today hard to get non detergent.i have always been told that if you run detergent oil after non detergent oil that it will bread down the sludge in a motor. however just read a article that said this is not true. anybody heard of this.

Arrowsmith: 3/16/2000 - 8:44:07 AM
RE: Oil brand & weight
I had a 68 car that I got used. it had about 2' of sludge on the heads. I ran detergent oil in it for 100,000 miles. the only problem I had was when the water pump went out and over heated. the sludge got hard and would stop up the oil hole in the push rods. I use mobil 1 15-50 all year

mr bill: 3/16/2000 - 9:50:43 AM
RE: Oil brand & weight
Like I said, most guys are running at least 40 or 50 weight. Looks like most are using multi-weight.

Bill M: 3/16/2000 - 12:22:50 PM
RE: Oil brand & weight
JWL is right run 20 -50 oil and by all means get an oil filter for the motor, and for whats its worth the w in 20w50 oil means the oil was tested at 0 degrees the oil will flow like 20 weight oil at o degrees, and flow like 50 weight at 210 degrees, all other oils were tested at 210 degrees, which means the oil is thick when cold

rumble seat: 3/16/2000 - 2:23:26 PM
Bill M. As usual, everyone has their own opinion on oils. I believe everyone should run what they feel is the best oil and weight and I don't try to sway them one way or the other. But, I have to disagree with your statement that 20w/50 flows like 20wt at 0 degrees and like 50wt at 210 degrees. I think it means you have the protection of 10wt at zero degrees and the protection of 50wt at 210 degrees. Think about it..... Doesn't oil pressure decrease dramatically as the temperature of the oil increases? Isn't this a sure sign the oil is getting thinner? If it gets thinner, doesn't it pour easier? If the oil does have a reverse viscosity index as you suggest, then at what temperature does it become 20wt? 30wt? 40wt? 50wt? I know many guys here in Denver are running 20w/50wt in their flatheads and swear by it. I don't use multi-vis oil except when breaking in a new engine and then I run 10w/30 for the first 100 miles only. My opinion: When hot, multi-vis oils don't provide as much rod bearing cushioning as a straight weight oil does. Try this: Get a can of 40wt and one of 10w/40. Put them on the same burner of a stove and heat them to 200 degrees. Which pours slower? The 40wt does.... a whole lot slower. A sure sign the oil is thicker. If it's thicker, it's got to have better cushioning on loads. This cushioning is needed if you're running hour after hour at high speeds when the weather is above 70 degrees to prevent undo pounding on the bearings. I agree the oils today are FAR superior to the old oils due to better refinement and better additives. I also agree the thinner oils are better on initial start up since they get to all the oiling points a lot quicker. Some years ago Ford and GM stated (in bold letters) in their owner's manuals that the use multi-vis oils that exceeded a spread of 20 (10w/30 is okay but 10w/40 is not) would void their engine warranties. This was because it could score pistons and cylinder walls. Another point I would like to make. I believe the use of multi-vis in our flatheads is okay as long as it's cool outside and the trips are short and the engine isn't run at sustained rpm's above 2500 rpms. If you're curious, I run 30wt Valvoline in the winter and 40wt Valvoline in the summer.... the same recommendations 'Ol Henry made.
Please note that, as usual, these are just my opinions.... rumble seat

JWL: 3/16/2000 - 6:07:41 PM
RE: Oil
I don't have time to go in depth on this subject, but to help keep facts available for readers I will present some statements taken directly from the relevant SAE and ASTM publications. '' When oils are identified by more than one SAE viscosity number, the ''W'' number designates the viscosity at 0F and the higher number without additional symbol, designates the viscosity at 210F.'' One other point which may be interesting: The Nascar Ford engines prepared by Robert Yates use 20-50 oil. I doubt that would be true if it only protected engines during cool, slow, drives. When I have more time perhaps I will try to explain the advantages of Multi-Viscosity over single viscosity oils. Or perhaps someone else here, who has studied the subject more recently than I, will present some information.

Bill M: 3/16/2000 - 10:07:13 PM RE: Oil
I'm qouting from a statement made by the S.A.E. they are the ones that set the standards and do the testing, they test the oil at 0 degrees to see if it flows like 20 w, they also test the oil at 210 degrees to see if it flows like 30 w

JoeW: : 3/16/2000 - 9:00:16 PM
I didn't mean to stir up a hornet's nest with my question about which oil is the best for my 41 Ford. In order to put to rest the question of oil viscosity, I went to the source and found out the following: Multi-weight oils (e.g. 10W30 etc.) are made possible by adding polymers to oil. The polymers allow the oil to have different weights at different temperatures. The first number indicates the viscosity of the oil at a cold temperature (usually 0 degrees F), while the second number indicates the viscosity at operating temperature. At cold temperatures the polymers are coiled up and allow the oil to flow as their low numbers indicate. As the oil warms up the polymers begin to unwind into long chains that prevent the oil from thinning as much as it normally would. the result is that at 100 degrees C, the oil has thinned only as much as the higher viscosity number indicates. Another way of looking at multi-vis oils is to think of 20W-50 as a 20 weight oil that will not thin more than a 50 weight would when hot (operating temp). I also posted this same question at 2 other sites and got a similar response there. The results so far are: 7 say use multi-vis oil ranging from 10W-40 to 20W-50. 2 people recommend either a straight 40W or choose between 30W, 40W, or 50W. I also asked Pennzoil/Quaker State, and they said to use 30W in the summer and 10W-30 in the winter. I asked Valvoline and they just said they don't have any data prior to 1950, and therefore could not make a recomendation. In summing up, I would like to thank everyone who took the time to respond to my question, and I will make a choice based on all the answers I received. By the way, if anyone wants to get all the technical data to compare different oils, check out the above link. THANKS AGAIN EVERYONE.

Bill M: 3/16/2000 - 10:21:53 PM
RE: Oil
Hey you didnt do any thing but get several opions, and rumble seat is pretty smart, i like to read his information, and discussions is the way information gets past on

BillA: 3/16/2000 - 11:05:40 PM
RE: Oil
Thanks Joe W. for the link information. It is a handy item to have around. I cut a copy for the guys a the local NAPA House. Some of the guys there are a little slow on oil knowledge. A person would be able to read this data sheet and make an intellegent deciscion on oil. Thanks again. Bill Abendroth

JWL: 3/17/2000 - 7:18:31 AM
RE: Oil
Thanks for the link. Many people just don't believe the fact that multi-weight really IS what it says. There are too many advantages with it to ignore. Maybe your link will improve the level of understanding.

rumble seat: 3/17/2000 - 3:29:54 PM
RE: Oil
JWL: First off I want to say that I respect your extremely vast knowledge of engines and I'm not trying to start an argument. But if the viscosity is as you state, then why does the oil get thinner (and pour easier) as it heats up? Why does oil pressure decrease as it heats up? In my opinion, when oil viscosity increases, oil pressure increases. And mine sure doesn't. New engines have superior engineering and design, not to mention machining, than the flathead has and is a main reason they lend themselves to multi-vis. Concerning Yates... if he were running flatheads (with their antiquated design and engineering), I seriously doubt he'd be running 20w/50.... even with his superior machine work and basically unlimited resources. I know from first hand experience that flatheads on a roundy-round track will eat bearings and cranks if multi-vis is run. I lost 5 engines in 5 races in the mid-50's running 10w/50 Humble oil during a hot summer in Corpus Christi Texas. Changed to straight 50wt Phillps 66 and ran the same bearings and crank for the rest of the season with no problems. One thing that puzzles me, at what temperatures does the oil change to the various weights?

rumble seat: 3/17/2000 - 4:17:22 PM
RE: Oil
Joe W. I studied the link concerning oils. I note they did not include any straight weight oils. If the viscosity is as they state, then why will an engine have more oil pressure with straight 40wt than it will with 20w/50 (both oils at the same temp)??? I understand about the polymers and how they act, but I have a real problem believing the viscosity increases with temp because of what the oil pressure gauge tells me. JWL brought up about R. Yates running multi-vis. I chatted with Vern Raymer, who was #1 alcohol dragster in the USA for 8 year straight years in the '80's and was world champion two of those years, concerning oils. He said he lost several Aries and Donovan aluminum engines running Pennzoil 20w/50 multi-vis. Many times the engine would only last a few runs. Tear down always showed scoring and heat. The cylinder walls, bearings, rods, crank, and pistons (many times the engine blew and destroyed almost everything) were all damaged and had to be replaced. Very expensive to say the least. He made no other changes except to change to straight 60wt Pennzoil and the problem stopped. Guess I should have kept my mouth shut on this subject.

JWL: 3/17/2000 - 4:36:04 PM
RE: Oil
It is true that the oils with heavy polymer content do not do well when they are dilluted with alcohol and/or nitro, which is the case with the type of engine described by rumble. Even though the oil is changed after each quarter mile run it flows from the crankcase as a creamy, foamy, brown mess. However, this in no way reflects the type of performance we can expect in our street cars. Also, although it may go against logic, the 20-50 oil WILL have a higher vicosity at 210 degrees than the 40 weight.

JoeW:3/19/2000 - 9:58:35 PM
RE: Oil
I totally agree with you. I think the oil companies have introduced a fudge factor into the multi-viscosity formula. It's been my experience through the years that a straight weight oil will hold a higher pressure than a similar graded multi weight oil, which leads to the logical conclusion that it will be thicker also. I think the key to understanding their claims is to remember that a 20W-40 oil, is a 20 weight oil with characteristics SIMILAR (not neccessarily better) to a 40 weight oil at operating temperture. And the real reason they start with a light weight oil is for better lubrication at start up. But all this aside, I still don't know what oil to run in my 41. I don't know the history of this car, as I bought it through a broker, and not the owner. I think I'm going to play it safe for the time being and use a non-detergent straight weight oil for now. I thank you for your comments, and I'm sure I'll be back to pick your brains as I try to solve other problems with this car.

rumble seat: 3/17/2000 - 5:04:08 PM
RE: Oil
Why will the oil pressure be less?

rumble seat: 3/27/2000 - 8:33 PM
RE: Oil
I find it interesting that the two people that wrote the SAE article everyone is hanging their hat on about multi-vis oils left E-mail addresses that are no good. I tried writing them both with a few questions only to find out the E-mail addresses were no good. Strange isn't it?
I also find it interesting that JWL or anyone on our forum can't tell me why the oil pressure decreases when the oil is hot IF the oil actuall gains in viscosity as all state. They just ignore this fact. And no one, including Pennzoil, Quaker State, Castrol, Valvoline, Hot Rod Mag, and two independent oil analyzers will not answer my typed queries concerning multi-vis oils.
Questions were: 1) Why does oil pressure drop if the viscosity increases?
2)At what temperatures does the oil change to the various viscosities?
3) If you mix a quart of 20wt and a quart of 40wt, what weight oil do you have?
Seems funny not one would (or could?) answer these relatively simple questions.

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