Oil recommendation: '67 Cadillac Deville

[serebin]

I got a bit of what might be rod knock with the 10w40 Castrol High mileage that's in there right now. It's only there when engine is cold and goes away after a minute.

Should I still be changing to 15w40 HDEO or would something else be better?

Thanks again.

 

[JT1]

Sounds like piston slap, it happens. No oil is going to change that.

If consumption has dropped you could try to find a 10w30 HDEO but I think that 15w40 would be about ideal.

 

[Robenstein]

Originally Posted By: serebin
I got a bit of what might be rod knock with the 10w40 Castrol High mileage that's in there right now. It's only there when engine is cold and goes away after a minute.

Should I still be changing to 15w40 HDEO or would something else be better?

Thanks again.


Yeah its probably piston slap. When the pistons warm up they expand to fill the cylinder better and the noise goes away.

 

[occupant]

I tried to buy a 1966 Sedan DeVille back in 1994. What shied me away from it was that it had been sitting for two years and when the guy at the motorcycle shop went to fire it up, it had a double knock sound, which he claimed was indicative of a wrist pin failure. So he shut it down and halved his asking price from $700 to $350 but I still was afraid to buy it. Nice car though, light blue outside, dark blue inside, factory air, AM-FM radio, and no rust whatsoever.

And then I bought a seriously rusty '75 Cutlass Supreme sedan for $100 with what turned out to be two cracked heads. I spent $700 to have both heads replaced with new gaskets, rebuilt carb, new belts and hoses, and then on top of that I bought a battery and a starter. Then sold it for $250. Go figure.

The Cadillac would have been cheaper to fix in the long run, I think. And I a) would have got more money when I sold it b) wouldn't have sold it and c) wouldn't have lost so much stuff out of the trunk when driving due to the huge holes in the Cutlass's quarter panels.

 

[Rumble]

Nice car! Make sure your carb/choke is functioning properly. If it's hard to start when cold, that can add unburned fuel to the oil, and can cause knocking or valve chatter due to oil being too thin.

I use to be in the vintage Cadillac parts business, and had many 50/60s Caddys through the years. BTW, I see you need some fender and door moldings. Have you taken them off, or are they missing?

 

[XS650]

Originally Posted By: serebin


Something else that was troubling was when I took off the oil filter, it was SOOOO HEAVY. Even after dumping out the oil that was in it. I'm talking at least twice as heavy as the brand new oil filter, maybe even three times as heavy. They were different brands of manufacture...but, I had never held a oil filter so heavy before. Maybe I can find it and cut it open.

Is it possible that the oil hadn't been changed in so long that it was burning oil at that rate? Whatever the case, it seems to be running well now.

I only just realized it hasn't been burning oil, because I only just changed the oil less than a tank ago.


That's a beautiful old car. If you drove it from San Fran to San Diego, the highway trip might have freed the rings up enough to reduce oil consumption.

I agree with Addyguy that a few frequent (1000-2000 mile) oil changes with some MMO in the oil for a while before you change it could be a good thing. Drain it while it's hot, more sludge will run out of the oil pan that way.

Please find the old filter and cut it open, it should make for some entertaining pictures.

 

[XS650]

You can find a brochure and a Fisher body manual here.
http://www.oldirononline.com/

 

[Dieselsrule]

Serebin,
That Cadillac looks great, thanks for posting pics. Back when it was new Straight 30wt oil was popular and I bet your car probably only went 2000 to 2500 on a qt when it was new.

If you drive it often and change oil regularly it will probably improve on oil consumption. I've bought older vehicles that drank oil at first and as I drove them the oil comsumption decreased. I would recommend a 15w40 diesel oil or 10W-40 High Mileage oil. A little Marvel Mystery Oil in the gas would help the valves also.
Enjoy that Caddy!

 

[Trvlr500]

I have a '73 Coupe which has been my only car for almost 15 years. Considering where you live 20-50, 15-50 or 15-40 is fine. The only reason I use 10-30 right now is because it gets cold in the winter where I live.

Your Caddy was probably abused like the vast majority of them are. The oil was probably never changed regularly. I would suggest some Rislone and frequent oil changes until the oil stays clean.

The other thing about the old 429-472/500 motors is that they don't like to sit and they HATE in town driving. They were built to run at 80 to 100 mph all day long which is when mine runs the best. They are geared so high that they never ever get into their torque band around town.

You probably have some stuck rings which frequent oil changes and Rislone will fix eventually. Provided there is no damage due to the oil never being changed cleaning it out will probably reduce your oil consumption or stop it.

I would also run MMO in the gas since it was designed to run on leaded fuel. It also needs premium gas and you may have to retard the timing even at that. I don't know off the top of my head what the CR is on that engine.

I don't know about the 429's but I have heard of the 472/500's going 3 and 400,000 miles. What they are is a diesel engine you put gas in. The problem is very few are taken care of and even fewer engine builders know the idiosyncrasies of rebuilding one right.

Get the engine cleaned out and get it out on the highway for a few good long distance high speed beatings. It'll either blow or start running a whole lot better. I had oil consumption problems with mine until I started driving it every day.

If you want access to the Cadillac guru's of the world go here:
http://forums.500cid.com/

They can answer ANY question you might have about that engine or they will point you in a direction of someone who can.

 

[UNC017]

Originally Posted By: Robenstein
Originally Posted By: 440Magnum
Originally Posted By: mechtech2
Cars used to use oil.
And cars with big engines used a lot.




Big-bore engines *still* use a lot compared to today's little 4 and 6-cylinders. Its all ring circumference. Actually swept area matters too, so its really cylinder surface area- but bore really does seem to increase consumption more than the same displacement but with a long stroke.





None of our big block Chevy's or Olds motors ever used any oil in 2-3k OCI's before 100,000 miles. We used 10w40 and 20w50 Castrol GTX in them with an occasional can of BG MOA in the 80's and 90's.


Well, a big-block Olds is actually a small-bore engine. An under-square torque monster- I love that thing. GM should have used it as the engine for their big trucks instead of the more fragile 454. The Buick big-block is a true big-bore engine with a short stroke and monster bore. A Chevy 454 is in between the other two.

My 440 really doesn't show a lot of consumption over just 3k miles either, but it won't go a 6k OCI without some make-up oil like the Jeep 4.0 will.

 

[Robenstein]

Well we bore all of our 454 motors out to 468 cubes. But because we love multiple carbs on our big blocks we never pushed past 3k miles on any oil change with conventional oil.

I will have to see how my 396 bored to 402 does when it gets shoe horned into my car in a year or so. Im going to have to run HDEO in it unlike the good old days when SJ GTX 20w50 did the trick.

 

[serebin]

Wow, thanks for all the great info. I am a younger guy who didn't have one of these great cars growing up, so any and all info is much appreciated. Thanks also for the links, I am definitely a RTFM (read the effin manual) type guy, so it's not wasted on me.

Yes, I have been running it on 91 fine with no pinging.

It is a little hard to start up, so I will have to read my Chilton (I got a real service manual coming on CD in the mail) on the fuel system.

 

[Powerglide]

Replace those valve stem seals.