Time to get the big Olds back on the road here in central Canada. But first: I've always used 10W-30 viscosity oil. But is there any reason not to use 10-40 in my '66 Olds (original 425, 160,000 miles)?

I ask because my father in law has some old cases of Quaker State oil from the 1990s, when I believe they still had zinc in them. Would be nice to use them up, unless there's an issue.

Thanks.

-Paul

 

They say the shelf life of oil is 5-8 years depending on how it's stored. I would burn it up in garden equipment. Oil is not yet expensive enough to take short cuts. I quit using Quaker State back in the 80's when they screwed up the formulation of their multigrade oil forcing a recall. If you do decide to use it, shake well.

 

X2, I would not use it. I'd use 10W-30 or
15W-40 Rotella or Valvoline VR1.

 

^^^THIS^^^

MAW get some good oil.

 

NOT Rotella, too much detergent.
Virtually ALL of the cam companies tell you NOT to use the diesel oils for that reason.

 

Thanks Mark I had forgotten about the diesel oil detergent.

 

Damn, I did not know oil had a shelf life. Been using up my father in law's old 10-30 for a couple years now. I guess I won't dip into the 10-40 then.

I put limited miles on these cars over the summer months only, but I will go out and buy some of the good stuff.

Appreciate the quick responses.

 

Lucas hot rod 20w/50 oil is pretty good as well, you can get it in the weight you like as well.

 

If the engine is stock, why would you not use the factory recommended viscosity? Does the Internet know more than the people who designed the motor?

 

Joe, with 160K on that 425, is it not possible that the clearances are a little looser than they were in 1966 and OP might be able to improve oil pressure and coax a few more miles out of the old beast by going a little heavier?

 

Joe, I don't know what the factory recommended viscosity is. Fill me in, please.

 

Our company which makes it's own oil at their refinery says 5 years. Lake Speed Jr says the same. I used some SL oil a year or two ago, just used up SM 10W40 in my Dakota last year. Only a Dodge but wouldn't use it in something I care about after seeing Lake test old oil, it didn't do too well. As said, VR1 is a good choice.

 

So I guess these really old cans of Quaker State are out of the question, lol. He still at least 10 of these, too.

 

Those can be worth like $100 per can on ebay if they are full! I've sold a few. Those could finance quite a few oil changes with new oil, filters, and even job beer! lol

 

Your owners manual says use 10W-40 in warm weather and 10w30 in extreme cold. Has you motor ever received a timing chain replacement? If not its overdue.

 

And you've had no problems? Seems to me you are trying to fix something that ain't broken.

I've always used 10W-30 or 10W-40 in my engines pretty much interchangeably, buying whatever's on sale. The owners manuals always recommend either for about the same temperature range and type of use.

I would not use old oil, even if in a never-opened container. Older oils do not have the current additives that have improved oils over time. As has been noted, oil is not expensive, and it's not as though you change it every week. Sell those old cans on ebay and make some money off of them.

 

As previously mentioned, I would save this stuff and sell it on ebay. It is rare to have cans this old with the oil still in them. For what you should get, you can buy lots of oil changes with new oil.

 

[QUOTE=jaunty75;1571372]And you've had no problems? Seems to me you are trying to fix something that ain't broken.

I've only used the old oil the last couple years. It looked fine, but I'm going to err on the side of caution, as most of us on this forum would probably do as well.

Just spoke to the man who rebuilt the 350 in my Cutlass three years ago. He's not sure about the old oil going bad, but he agrees: play it safe, get the Valvoline VR1. And he knows exactly where I can get it. (He's also not a fan of zinc additives).

Thanks again.

Paul

 

As for the old Quaker State cans (my father in law has nearly a dozen full ones), I think I'll hang onto 'em. Maybe find a vintage rack or stand for them and make a garage display some day.

 

Here in NorCal, I started with 10/40 for first decade or 2 in my 455’s, then somewhere along the way switched to Vavoline VR1 20/50 and have been happy. I think I went with VR1 for the zinc content, plus the Lucas Oil stabilizer secret sauce. That combination seems to be working,

Our temperatures here by San Francisco vary from around 40F-105F across the year. I usually change the oil 2-3x per year so fresh stuff is usually in the crankcase regardless of (pretty limited - <~5,000/year) mileage. I always feel the engines smooth out when fresh oil is in the crankcase.

Am I roughly on target assuming no blue smoke on startup & reasonably regular use? Would I benefit from any other oil weight than 20/50?

I have the unfounded opinion that I don’t want synthetic since it might create/find leaks. Of which I have a few to live with. So why exacerbate the problem?

Suggestions or experiments warmly welcomed.

Chris

 

Assuming a healthy engine and given the mild climate in Northern California I don't know why you'd use anything other than 10W-30. It is my feeling (also admittedly based on no data whatsoever) that using an oil too heavy will result in accumulation of sludge and accelerated wear.