News:

Due to a technical issue, some recently uploaded pictures have been lost. We are investigating why this happened but the issue has been resolved so that future uploads should be safe.  You can also Modify your post (MORE...) and re-upload the pictures in your post.

Main Menu

What wt/viscosity oil for my 67 Coupe DeVille???

Started by Asa Mulinix, August 30, 2010, 06:25:10 PM

Previous topic - Next topic

0 Members and 1 Guest are viewing this topic.

Asa Mulinix

Ok....As stated previously, I'm new to the Vintage Cadillacs....I don't yet have a shop manual (got several on my watch list on Ebay) so I'm pretty much just running by the seat of my pants here.  I was in the parts store the other day and I picked up an oil filter and five qts of oil.  I picked up 10w40 just like I would put in any of the small block chevies I've owned...Then it occurs to me that this isn't a small block chevrolet.  So I come in and put Google through it's paces searching for something that'll send me down the right road to new found knowledge about my Cadillac...Apparently my search skills are lacking.  I did find one blog where a gent mentioned using 5w30 in his 67 Cadillac.  Of course a blog is like a bathroom wall...anyone can write on em but it doesn't make what they write the truth....So,  I'm asking.   What oil should I be buying for my 1967 Cadillac Coupe DeVille?

Thanks guys,

Asa Mulinix

35-709

#1
Did you get an Owner's Manual with the car?  It would recommend 10W-30 for most conditions.  10W-40 will work just fine especially in an engine that has accumulated some miles and is what I normally use here in FLA.
Geoff N.
1935 Cadillac Sedan resto-mod "Big Red"
1973 Cadillac Caribou - Sold - but still in the family
1950 Jaguar Mark V Saloon resto-mod - Sold
1942 Cadillac 6269 - Sold
1968 Pontiac Bonneville Convertible - Sold
1950 Packard 2dr. Club Sedan
1935 Glenn Pray - Auburn Boattail Speedster, Gen. 2

bill henry

I only drive my 70 in the summer and I use sae 30wt high detergant Valvoline + 1 pint GM EOS.
Bill Henry

Asa Mulinix

The only paperwork the car came with was a title...no other documents of any kind... so I'm really flying by the seat of my pants on this one. 


william_b_noble

I use 10W40 in my older cars- 1938 to 1959 inclusive - you could use 5W40 but I would want the 40 part unless your engine is newly rebuilt.  originally most of these older cars wanted 30 wt per the manual, but by the late 60s multigrade was common.  

It would behoove you to buy an original (or reproduction) shop maual for your specific car, not a chiltons
Bill N - clc # 2371

The Tassie Devil(le)

I use 25 W 50 oil in all my cars.

But, they are all high mileage units.   Cannot afford new stuff.

Bruce. >:D
'72 Eldorado Convertible (LHD)
'70 Ranchero Squire (RHD)
'74 Chris Craft Gull Wing (SH)
'02 VX Series II Holden Commodore SS Sedan
(Past President Modified Chapter)

Past Cars of significance - to me
1935 Ford 3 Window Coupe
1936 Ford 5 Window Coupe
1937 Chevrolet Sports Coupe
1955 Chevrolet Convertible
1959 Ford Fairlane Ranch Wagon
1960 Cadillac CDV
1972 Cadillac Eldorado Coupe

dadscad

In my 63 with the 390 I'm using full synthetic Amsoil 5-30 gas/diesel oil. Lots of zinc/phosphorus additives to protect the cam and lifters. My manual called for 20w/20, and 10-30 oil. A 5-30 oil will work in place of the 10-30. It is still a 30 weight at temperature but flows as a 5 weight on start up instead of a 10 weight. On start ups after sitting for long periods of time, a 5 wt. will reach vital parts quicker. Until the government mandated additive reduction, I used the full synthetic 0-30 Amsoil motor oil in the 63. Still do in my daily drivers.

For your information I attached a bulletin you may find interesting.
Enjoy The Ride,
David Thomas CLC #14765
1963 Coupe deVille

Steve W

Asa, I do not know your location, but here in Los Angeles I use Penzoil high-mileage formula 10-30, and then add one 12 oz bottle of 'hy-per lube ZRA' in my 68 CdV.
The hy-per lube stuff is just an additive that is supposed to help our older engines survive without the zinc and other products that used to be in our oil back in the day. I do not know if it really works or not, but it's kind of like the placebo effect..I THINK it probably works...and the car doesn't complain! My car has 180k miles.  I may be spending a bit too much at oil-change time, but I would like to think that I am treating my car to 'nothing but the best'.




Steve Waddington
1968 Coupe deVille
North Hollywood, CA
CLC Member # 32866

Otto Skorzeny

Quote from: Steve W on August 31, 2010, 05:11:33 PM
...it's kind of like the placebo effect..I THINK it probably works...and the car doesn't complain!

I think that's a perfect description, Steve.
fward

Ask not what your country can do for you, but what you can do for YOURSELF

HUGE VENDOR LIST CLICK HERE

Asa Mulinix

Thanks for all the input fellas!  I got her oil changed today and went back with 10w40. 

Just for the sake of conversation I'm located in NW Georgia...and it's an 81K mile car.

Chris Conklin

I still use 30W per the manual in my '66 (Valvoline), and change it too often (every 2K miles). I'll toss a little Marvel Mystery Oil in there from time to time as well (like Steve... the placebo effect... must be a Los Angeles thing  8) ). A few things I'm curious about;

It may just be a local problem here in Southern California, but I sometimes have difficulty getting a single grade 30W quart of oil. Anybody else? Probably just an issue of what sells is what is stocked and that is multi-grade oil.

I've seen people mention in quite a few posts that they use a somewhat higher weight multi-grade "in all my older cars" (10W-40W instead of 30W, for example). Do you feel that will protect and extend the life of the engine better than the original single-grade recommended? And why? Or is it just because you can assume some looser tolerances in the older engine? How did you determine the alternate weight needed in the multi-grade you are using? Again, just curious. The market may make me switch at some point.

My car data: Original engine that shows no signs of a rebuild, 56K on the odometer - could be 156K. All visible indications support low mileage as do any non-invasive tests, anything that can be gauged has been and is within 1% of original specs. I'm the third owner. Loses no oil or other fluids. The owner's manual states that replacing one quart of oil every 800-1,000 miles is normal, doesn't even need that. It is my driver, but that means about 3-4 days per week and about 7K miles yearly max, closer to 5K most years.
Chris Conklin

Steve W

Chris, in the older cars ( flat tappets, etc,) they say using the heavier oil gives more protection and helps with the looser tolerances and overall wear and tear. But does it really? Placebo effect again? I don't know, but I tend to err on the side of safety if at all possible, so I stick with the high-mileage formula 10w30 and use the additive (BUT I have a reason for it which I will get to in a second).  And I'm sure here in Southern CA, 30w is just fine, especially since you have 100k LESS miles than me.

I know some guys who will tell you that you have to use LEAD as an additive in the gas for these older engines if you didn't have the valves "hardened" because the premium gas back when our cars were new had lead in it and the lead somehow was good for the engine.

I had a couple of mechanics tell me that the smaller engines need the lead, but that the big blocks usually don't. (Lower revs) And I have had Pontiacs, Chevvies, Fords, BMW, Mercedes and now the Caddy and never had the "valves hardened" and never had a problem running 91 octane (the highest grade we can get here in CA) in any of my old classics. Oh yeah, that's another one, octane. Our cars were designed to run on 93 or more octane, so we better get octane boosters too!

The reason I use the high-milage formula 10w30 with the aditive is this: I want as much protection for the internals in my engine as possible, without adding "gunk". My car has 180k miles on it and I have every service record going back to its first wheel alignment in 1968, and the motor has never been rebuilt. The previous owners used Penzoil or Valvoline either 30w or 10w30, so that's what I stick with.
I believe the 10w helps at start-up and the 30w is just about right for everything else without adding too much viscosity for the oil to flow freely everywhere it needs to go. And I use the additive because from all the reading I have done, apparently they have re-formulated engine oils since 1968 and removed zinc and phosphorus which some say our older engines need. I am sure after 180k miles I have a significant amount of "sludge" inside the motor, that's just normal. But I change the oil every 2-2.5k miles and it still looks clean. I don't want heavy detergent oil, don't want to do an engine "flush" because I don't want sludge chunks breaking away and clogging any oil lines or whatever. So I stick with regular oil changes and the additive. Placebo...sure, but with a little research behind it.

If I had a fresh motor, or a fresh rebuild, then after break-in, I would use synthetic or synthetic blend because it seems to give better protection and its more readily available.

But for now, call me Placebo Boy!

Steve Waddington
1968 Coupe deVille
North Hollywood, CA
CLC Member # 32866

35-709

"I know some guys who will tell you that you have to use LEAD as an additive in the gas for these older engines if you didn't have the valves "hardened" because the premium gas back when our cars were new had lead in it and the lead somehow was good for the engine."

When gas was leaded all gas was leaded, Regular, Mid-grade, and Premium (except for Amoco). The myth that older engines that were built during the leaded gasoline era need to have hardened valve seats installed (the valves are not "hardened") lingers on.  For engines used in normal day to day driving it is a waste of time and money, if desired the hardened seats can be installed at engine overhaul.  Most cars are junked if their engines need to be overhauled.  Older engines used for heavy/severe duty such as marine engines, racing engines, and engines in vehicles that frequently pull heavy loads, will benefit from hardened valve seat installation.    
Geoff N.  
1935 Cadillac Sedan resto-mod "Big Red"
1973 Cadillac Caribou - Sold - but still in the family
1950 Jaguar Mark V Saloon resto-mod - Sold
1942 Cadillac 6269 - Sold
1968 Pontiac Bonneville Convertible - Sold
1950 Packard 2dr. Club Sedan
1935 Glenn Pray - Auburn Boattail Speedster, Gen. 2

The Tassie Devil(le)

G'day Chris,

I use 30 weight oil in my boat motor, and as most marine engines makers recommend single viscosity oils, try your nearest Marine Shop.

The reason for the Single Weight Oil is that a Marine Engine spends 99% of its' operating time at or near maximum revolutions, hour after hour, all day long.

Bruce. >:D
'72 Eldorado Convertible (LHD)
'70 Ranchero Squire (RHD)
'74 Chris Craft Gull Wing (SH)
'02 VX Series II Holden Commodore SS Sedan
(Past President Modified Chapter)

Past Cars of significance - to me
1935 Ford 3 Window Coupe
1936 Ford 5 Window Coupe
1937 Chevrolet Sports Coupe
1955 Chevrolet Convertible
1959 Ford Fairlane Ranch Wagon
1960 Cadillac CDV
1972 Cadillac Eldorado Coupe

dadscad

If you have an engine that has loose tolerances from wear, a heavier oil is suitable to help cushion and fill the spaces. If you have an engine that is in good tight condition, a heavy oil will impede oil flow to vital parts where the thinner oil will flow more readily and lubricate/cool better. Oil is not only a lubricant but a coolant carrying away heat from internal parts to help cool them. Oil flow is important to keep bearings and pistons etc. cooled as well as lubricated. A thick oil absorbs heat slower than a thinner oil and flows slower causing stressed parts to run at higher temperatures which oxidises the oil quicker. Unless the manufacturer calls for a thick oil you could cause excessive wear using it in a sound engine that calls for a 5-30, 10-30 or 5-20 etc. oil. The thicker oil will flow slower on start up causing excessive wear and flow slower even when hot because it is too thick to flow into the tight tolerances in the engine. A thick oil has it's place, but not in a mechanically sound motor that calls for a thinner motor oil.

Putting additives in a properly formulated motor oil is not necessarily a good thing. The oil manufacturer chooses compatible additives that compliment each other, putting in another batch of additives could cause adverse reactions between the different additives and actually degrade the performance of both products.

Enjoy The Ride,
David Thomas CLC #14765
1963 Coupe deVille

Steve W

DadsCad, you are pretty much right on, as usual.

However, there are SO many discussions and theories out there regarding older, higher-mileage vehicles, there doesn't seem to be a clear 'one-size-fits-all' answer.

Just for discussion...

""The oil manufacturer chooses compatible additives that compliment each other...""  Yeah, but it seems the feds had something to say about it too. And the car manufactures found out that they had to have catalytic converters to meet emissions standards, but zddp was killing converters, so they removed it. So..what does that do for our older, non-catalytic cars that "the oil manufacturer chooses compatible additives that compliment each other" back in 1967? The oil of today is not the same as the oil of 1967. Unless you seek out the special oils. They are making oil for today's cars.

And you brought up a great point about oil helping to dissipate heat!

I'm lucky...I knew what the previous owners used and when they changed it. But the Penzoil they used back then had all that zddp stuff in it. Even if I use the same brand, Penzoil, its not the same formula.

However, on some of these cars, who knows what the previous owners put in them...peanut oil and a tolet paper filter? They may have a lot more wear and looser tolerances. They may benefit from additives and/or a slightly heavier viscosity...but even then I would use multi-grade...like a 10w40.

And what about that "Marvel Mystery Oil" Chris? I read a lot of posts about that stuff too...isn't that actually some sort of solvent? (that smells like Pepto Bismol!) Wouldn't it thin the oil out?
Steve Waddington
1968 Coupe deVille
North Hollywood, CA
CLC Member # 32866

dadscad

Thank you Steve.

Actually, todays oils are much better than what was available back in the 60's etc. The additives are of higher quality and the chemistry is more advanced. That is why todays vehicles can go up to 7500 - 10000 miles on an oil change using refined petroleum oils, even longer on properly formulated synthetics!

True enough, todays mainstream oil formulations are designed for todays crop of vehicles. But, there are oils with with adequate ZDDP and Phosphorus along with other compatible quality additives and base stocks that will work very well in our older vehicles without using supplemental oil additives. By adding ZDDP to a good quality mainstream oil, such as Pennzoil that has the mandated reduced ZDDP, could adversely affect the additive package Pennzoil used to replace the reduced ZDDP. Rest assured, when Pennzoil reduced the ZDDP they added a compatible additive to take up the slack with respect to todays vehicle requirements.

I agree, when the condition of the engine is unknown it is best to err on the side of caution. Generally speaking, if the motor does not make abnormal noise, holds good oil pressure and does not use excessive amounts of oil, I would consider it to be in good mechanical condition and would use the proper recommended grade of oil.

I used Pennzoil in all my vehicles for decades, with very good results. Since going with Amsoil synthetic lubricants, time and miles have proven to me, synthetic lubricants are on top of the lubricant ladder.

Have a great holiday!
David
Enjoy The Ride,
David Thomas CLC #14765
1963 Coupe deVille