Oil recommendation: '67 Cadillac Deville

[serebin]

Good evening Ladies and Gents!

I am looking for a oil recommendation for my '67 Cadillac Deville. It has supposedly 40K miles on it, but the odometer only goes to 99,999 miles, so who knows.

The owners manual recommends 30W oil for the vehicle at above 40F degree temperatures.

I am in San Diego. The lows right now are in the mid 50s, and I do not expect it to get much/any colder.

I drive easy as it's an older vehicle, but sometimes I do go on road trips of more than a few hundred miles.

I ride a mix of freeway and city stop and go, usually at least 15 minutes at a time.

The only problems that the car has is that it eats oil. I typically put in a half quart every 10 gallons. It does not leak.

I use synthetic oil in my motorcycles, but am unsure about running it in this vehicle.

I read your stickied post about oil recommendations and figured that I would get more consideration if I posed my question with the above info

Thank you very much for reading my post!

 

[JT1]

15w40 HDEO or 10w40 High Mileage of your choice. Really anything thats cheap with a consumption rate like that.

 

[Steve S]

Syn isn't needed it the Cad for sure. Does it smoke? Straight 30 would work well. Tell us more about the car. That is a sweet car. Built when Cads were something special.

 

[qship1996]

It is burning 1 quart of oil every 200 miles- buy the cheapest thickest oil you can find, like 20w-50

 

[serebin]

It's a 429. I really love it and don't care if I have to baby it. It's like riding around on a big comfy couch. The electric options all work, it's amazing. You can tilt the bench seat and everything. It's an awesome car to have a date, with the bench seat You can turn the thing with one finger, the power steering is great.

It is my only car, I was on my sportbike for a couple years straight. I just couldn't pass it up.

Here are photos of it (from the guy I bought it off)

http://www.flickr.com/photos/11142741@N04/sets/72157616109859867/

 

[serebin]

It doesn't smoke. I was thinking about 30W, but had heard that something like 10w40 would be better while the engine warms up, is that correct? Right now I have Castrol 10w40 high mileage.

Thank you for your replies.

 

[serebin]

After reading your replies and searching up on HDEO, I've decided to go with a 15w40 HDEO.

 

[JT1]

Good choice on the 15w40 hdeo. You won't even need to drain out your old oil, just introduce it as the old stuff burns off. then change your oil filter twice a year and your set.

you should try engine restore to see if that slows oil consumption, I've heard alot of good results with using it. I have also heard people *speculate* that it could damage an engine but have never actually read or heard about that happening. I have to believe it would've been pulled off shelves if that was the case.

 

[1WildPig]

Neat car ... Just throwing in a couple of suggestions ... the car was designed for leaded fuel so I'd think that running an upper cylinder lubricant (MMO) would be beneficial. Also, using that much oil, it should be smoking, maybe just not too noticeable - I'd check the PCV system and run some Marvel Mystery Oil in with that HDEO 15w40 for a couple of oil change intervals to help clean out the ring packs - can't hurt and may very well help a lot, after that, I'd be inclined to use a High Mileage engine oil such as Quaker State HM or Valvoline (synblend) HM ... Luck to ya!

 

[addyguy]

Very, very nice car. That bottom picture looks straight out of a Cadillac brochure!

Good choice on the 15W-40. To help with the consumption, give this a try: When your car is down a quart, add a quart of Marvel Mystery Oil (MMO) to the crankcase. Sometimes it help free-up piston rings and reduce consumption.

If that car is driven very gently, it may just have carboned-up rings. The above procedure should help, but if it doesn't, you may have to invest in a good, hard 'Italian Tune Up' to try and free the rings.

One final option, if you are brave and careful, is to do a water de-carboning. Get the engine good and hot, remove the air cleaner, and trickle distilled water into the carb while reving the engine, just a very little bit at a time. It's an old-timers trick that was done a lot on cars of this vintage. Some use ATF instead of water, but be careful, as you can lock-up the engine if too much goes in.

 

[serebin]

When I first received the car from the previous owner, it was burning a half quart per 10 gallons like he said. I then changed the oil from 10w30 (bought it in San Francisco) to 10w40 just recently. I am almost through a whole tank (20 gallons) since changing the oil and it has not needed any oil topped up, I just realized.

I can't imagine that changing the oil once has fixed it, but I will say the oil I got outta that car was terribly black... I asked the guy when the last time he changed the oil was after I bought it (text message), and received no response. I figured that was what people call a "clue", so I changed it immediately.

Another weird thing when I changed the oil was that I only got 4 quarts of oil out of it even though it was previously at the right level on the dipstick. However I was able to put in the specified 5 quarts as per the manual, and that was perfect when looking at the dipstick.

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.

 

[serebin]

And thank you very much for everyone's help! I do all the work on my motorcycle and and now this car, so I am very interested in any knowledge you may have about the lifeblood that runs through them.

 

[Robenstein]

Any good Diesel oil will work fine. I had a 70 Deville in high school with the 472 motor. Thing was a beast. I ran Castrol GTX 10w40 in it, but that was in the days before they killed the zinc in the oil.

 

[Andyge]

How about Mobil clean 5,000 10w-40


Andy

 

[440Magnum]

Beautiful old land yacht! Welcome to the world of vintage vehicles as daily drivers- my '66 Polara is my everyday car too. I've always had a soft spot for big Cadillacs because I've had a couple of friends who were really into them- one had a pair of 390-powered '59 DeVilles, and another has a 472-powered 72 Deville that's restored to near showroom quality (obviously not his daily ride...). The Cadillac v8s up to the 500 CID were just indestructible. The wheels fell off Caddy engine quality in the 80s, though- some really stinkers in there.

I agree with everyone who's said that an HDEO (diesel engine oil) is a good choice. My personal preference is Rotella T6 (formerly Rotella T Synthetic or RTS) 5w40. I've never liked using 15w40s personally because my 440 sends the oil pressure off the charts on a cold start with a 15wXX oil and I worry about over stressing the oil pump drive gears (even though I've got the heavy duty extra thick and hardened intermediate shaft). But if your pressures don't go berserk, then the 15w40 should be fine.

As for the high oil consumption- did the previous owner drive it much? If not, you've probably got some stuck/gummed oil control rings. Using an HDEO, doing a few short interval oil changes, and just *driving* it may clear a lot of that up- I've seen that a number of times with cars that have spent a lot of time stored or rarely driven.

 

[addyguy]

Originally Posted By: serebin
When I first received the car from the previous owner, it was burning a half quart per 10 gallons like he said. I then changed the oil from 10w30 (bought it in San Francisco) to 10w40 just recently. I am almost through a whole tank (20 gallons) since changing the oil and it has not needed any oil topped up, I just realized.

I can't imagine that changing the oil once has fixed it, but I will say the oil I got outta that car was terribly black... I asked the guy when the last time he changed the oil was after I bought it (text message), and received no response. I figured that was what people call a "clue", so I changed it immediately.

Another weird thing when I changed the oil was that I only got 4 quarts of oil out of it even though it was previously at the right level on the dipstick. However I was able to put in the specified 5 quarts as per the manual, and that was perfect when looking at the dipstick.

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 heavy filter tells me your engine is sludged up from lack of oil changes......

Do a couple of short 1-2k oil changes on it, and as I said earlier, I'd add some MMO to a fill of oil.

Hopefully, as 440Mag said, some driving will help clear this big monster out.....

 

[mechtech2]

Cars used to use oil.
And cars with big engines used a lot.
It was normal to check the oil when filling up at the gas station.


The HDEO [diesel] oil in 115-40 is more suitable for that car and climate than any X-30. I'd use it for sure.

 

[addyguy]

Originally Posted By: mechtech2
Cars used to use oil.
And cars with big engines used a lot.
It was normal to check the oil when filling up at the gas station.


The HDEO [diesel] oil in 115-40 is more suitable for that car and climate than any X-30. I'd use it for sure.




Can't imagine that - I've never had a car that used an appreciable amount of oil.

I check my oil once a month or so, and it's always pretty well the same....

 

[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.

 

[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.