Hey everyone. I just got a 1980 Eldorado with the 5.7L Oldsmobile Diesel Engine. I was wondering if any of you knew what brand of oil i should use?

The previous owner told me this much:

Summer - SAE 30
Spring/Fall - SAE 15W-40
Winter - SAE 10W-30

And he said the "API Rating" should be at least "SF/CC" and/or "SF/CD"

So far what i've gathered is that i should use SAE 30 this summer, but im not sure what brand to get. Should i get Mobil Delvac, or Shell Rotella, etc.?????

Thanks to anyone who knows the answer to my question and replies.

I have the same engine in my car and if you look through all the postings you should be able to find a question I had similar to yours. There were some replies that really helped me out and if you can find it, it should answer you questions. Dirty

ps I will try find it and move it to your thread

Use either the Delvac or Delo or Rotella 15W40 oil that is currently available. That is excellent oil (all of them - I like the Delvac, myself) for heavy duty use. It really excedes all the oil specs that the diesel engine was developed around at the time.

The engine was originally spec'd for 30W oil as the multivis oils of the time had poor quality viscosity improvers that would stick the rings so no diesel manufacturers recommended multi-vis oils. Things change. Oils have dramatically improved since 1980. The current Delvac oil is a 15W40 multi-viscosity oil that easily meets the diesel specs due to the synthetic viscosity improvers used today.

The previous owner sounds like he knew what was going on and maintained the engine correctly. If it is still running 25 years later it must have had good care.

Search using the search feature in the tool bar above for the forum and use "diesel" in the search topic drop down box. There are several other previous posts on the diesel.

Basically, it should run a long time for you. Change the oil frequently as the soot in the diesel oil from blowby rapidly ages the oil. 3000 mile change intervals at the most I would say. Change the coolant frequently - yearly I would say and use the conventional green silicated coolant in the diesel.

Whatever you do, absoutely never be tempted to use starting fluid to start the engine!! It will wreck it as the high pressures from the spontaneous combustion of the ether will damage the pistons by bending the top ring lands down and trapping the rings. Just do NOT ever use any sort of starting fluid or starting aid. Plug in the block heaters in the winter. If it will not start in cold weather warm it up but don't use the ether. Most diesels of that era were ruined with starting fluid and the 10W40 oils of the day with the poor quality viscosity improvers.

Out of curiosity what is the mileage on the car/engine.

There are several good Olds diesel forums that you can locate with google.

Whatever you do, absoutely never be tempted to use starting fluid to start the engine!! It will wreck it as the high pressures from the spontaneous combustion of the ether will damage the pistons by bending the top ring lands down and trapping the rings. Just do NOT ever use any sort of starting fluid or starting aid. Plug in the block heaters in the winter. If it will not start in cold weather warm it up but don't use the ether. Most diesels of that era were ruined with starting fluid and the 10W40 oils of the day with the poor quality viscosity improvers.I'm well aware of that; id never try to start it like that anyways. Im afraid to mess with it too much, since it DOES run right now, i don't want to ruin that

Out of curiosity what is the mileage on the car/engine.

There are several good Olds diesel forums that you can locate with google.The mileage is about 125,000

and i did find a good olds diesel forums (olds-diesel.com), but everyone there was so opinionated that i couldn't get a good-solid answer. they were recommending this and that and all i needed was one answer.

So i will probably use Mobil Delvac and since you recommend 15W-40 i will try that. However, would it be okay to use SAE 30 in it this summer, or do you think that 15w-40 would be better? I was thinking about Delvac 1630 for it....


P.S., what brand of "conventional green silicated coolant" should buy?

I think the 15W40 oil would be the best accually. The straight 30 weight was specifically called out to avoid a multi-vis oil because of the problems with multi-vis oils of that era. The multi-vis 15W40 today is fine because of the better quality VI package as I mentioned. The multivis will help the cranking speed a little bit compared to straight 30W and will help with a little more rapid lube flow and it will give a little better fuel economy also. I would not be afraid to use it at all.

Read the jug on the 15W40 Delvac and you will see that it meets all the diesel specifications and is an SL rated oil. It is NOT rated per the GF3 or GF4 standards for gasoline engines specifically because it does NOT have the friction modifyers in it that the GF requirements need to meet the fuel economy improvement requirements. This is a good thing for your diesel.

If you were to look at 10W40 oils of the 1980 era you would see that they specifically did NOT meet ANY diesel specs and all the diesel makers (including Cat, Cummins, DDiesel) specifically did not recommend using any multivis oils. Similarily, the Olds diesel was specified for straight 30W under most conditions except where cold cranking speed was critical then the 10W30 was allowed as the 10W30 had much less viscosity improvers in it that the 10W40 of that era did. Things are different today as the oil quality has dramatically improved due to requirements specifically aimed at ring belt deposits with multivis oils so every oil today that is rated SL and is a multivis has synthetic VI packages that will not cause the deposits.

If the Olds diesel was produced today I am sure it would be spec'd for the Delvac 15W40 type of oil. I like either Prestone or Texaco green conventional coolant. Both were OEM suppliers of coolant and had excellent quality control. Any of the green coolants are silicated as that is basically what the "green" color indicates. Non-silicated coolants, such as DexCool , are different color, such as the orange of DexCool.

One other comment. I'm sure you know that the engine has glow plugs to enable it to start cold. If the glow plug controller dies the glow plugs will not activate and the engine will be hard to start cold. I mentioned the taboo of using starting fluid in this case. Also, don't be tempted to jump the glow plug controller and put voltage directly to the glow plugs. They can easily be burned out. Frequently, when the glow plugs are burned out from being overheated (from being jumped) they "swell up" on the ends of the heating element that is in the combustion chamber. When this happens they are hard to remove and often are impossible to remove. Normally, they just unscrew like a spark plug. If they swell up, they stick in the bore and will not some out so someone grabs them with pliers and yanks them out and the swollen up tip breaks off and falls into the cylinder - and if you crank it not it takes out the engine. Don't jump the glow plugs lest you confirm my dire predictions.

I think the 15W40 oil would be the best accually. The straight 30 weight was specifically called out to avoid a multi-vis oil because of the problems with multi-vis oils of that era.
Well, i kinda knew about that - that the oils today are much more advanced than they were 25 years ago. Since you think that 15W-40 is the best, i will get it.

Also, don't be tempted to jump the glow plug controller and put voltage directly to the glow plugs. They can easily be burned out. Frequently, when the glow plugs are burned out from being overheated (from being jumped) they "swell up" on the ends of the heating element that is in the combustion chamber. When this happens they are hard to remove and often are impossible to remove. Normally, they just unscrew like a spark plug. If they swell up, they stick in the bore and will not some out so someone grabs them with pliers and yanks them out and the swollen up tip breaks off and falls into the cylinder - and if you crank it not it takes out the engine. Don't jump the glow plugs lest you confirm my dire predictions.
Well, luckily for me i live in an area where it hardly ever gets that cold (i've never had to use the block heater). Also, as i mentioned before, im not one to mess with this car too much. It works right now, so theres no need to add WD-40 to try to start it or jump the glow plugs. I just leave it be for the most part, unless i can tell that something is wrong and needs to be fixed.

For example, last month i noticed that it was leaking coolant, so found out that the overflow reservoir had a huge crack in it and the engine had almost overheated once. Got that fixed, but now i think that im going to have to change the air filter. Its puffing out way too much black smoke for my liking; unless of course you think that there is something else wrong with it besides the air filter? Maybe its not getting enough compression or what?

Those diesels did smoke quite a bit. Not much you can do, really. Just the nature of the beast from back then. That is a 25 year old diesel not one of the current common rail engines with electronic controls and electronic injection. It is going to smoke. No concern with the compression I wouldn't think. If it starts well and runs good then the compression is fine. If had had a compression problem it wouldn't even start. Compression ignition engines are like that.

I had an 1982 6.2 diesel suburban that smoked like crazy. Replacing the mufflers with a set of high flow mufflers alleviated much of the smoking. Also, the intake manifold was pretty well clogged up with soot due to the EGR valve. I cleaned this out and it no longer smoked even at full throttle. Try taking off the air cleaner and look down the intake manifold and I bet that it needs to be cleaned out.

I had an 1982 6.2 diesel suburban that smoked like crazy. Replacing the mufflers with a set of high flow mufflers alleviated much of the smoking. Also, the intake manifold was pretty well clogged up with soot due to the EGR valve. I cleaned this out and it no longer smoked even at full throttle. Try taking off the air cleaner and look down the intake manifold and I bet that it needs to be cleaned out.

If you switched to a dual exhaust from the factory single exhaust the engine still smoked just as much you just see less smoke from each pipe so it "looks" like it is smoking less. Common trick with a lot of diesels.

The truck came from the factory with dual exhaust. All 1982 trucks that I've seen equipped with the 6.2 option or the 454 came with dual exhaust. Mine is the light duty half ton model with tall 3.08 gearing and overdrive automatic transmission.

Opening the exhaust up and turning up the injection pump made a big difference in power for towing my 6000 lb Airstream trailer. This is for an engine that put out 140 HP from the factory.

hey guys, here are some pictures of my Caddy that i've been talkin' about:

http://www.cardomain.com/memberpage/632008

Well, well ,well another deisel caddy owner. And with all the questions I had when I started out with my '79 Eldo.
It was a bit frustrating for me because I had to bring it back from years of not being used at all.
Between all the relays, and filters, and the tank cleaners that I went through it's a wonder that she's still in the driveway today.
When I first started running the engine it produced a black cloud of smoke that looked like the oil fields of Kuwait were aflame. Now it's behaving much better , but must beware, I live in Southern California, and the " Man" don't much care for that. Wel good luck I will be around.

When I first started running the engine it produced a black cloud of smoke that looked like the oil fields of Kuwait were aflame. Now it's behaving much better , but must beware, I live in Southern California, and the " Man" don't much care for that. Wel good luck I will be around.

Aren't diesels illegal to sell in California now??? Too toxic for the EPA regulations?

Wow, you have a first generation Olds diesel too. I had mine replaced with the later version (DX block) so it would last longer. If you haven't already checked it out bruski127, you might want to cruise on over to http://www.olds-diesel.com/

its a huge community of people who own old caddys, oldsmobiles, etc. with the 350 diesel engine.