straight weight vs multi-weight oil - 331

[bullet bob]

Let me start by saying I'm sorry, another oil thread. But I've done the search, and I can't find the answer. My mechanic says I need to run a straight 30W in my "53 331. I understand that's what it called for, "back in the day." But I've been running 10W30. along with a bottle of DZZT, or whatever it's called. Has the optional oil filter. Do I go back to a straight 30W or is the 10W30 OK? Thanks all. BB

[Philippe M. Ruel]

These engines needed 20W in the summer (30W under hot climates) and 10W in the winter, involving draining oil twice a year.

Fortunately a few years later someone invented multi-weight oil that all 331s could use, and they lived happily ever after.

[TJ Hopland]

My 2 cents knowing nothing specifically about the 331.   As you said at one point multi viscosity oils didn't exist and when they first came out there were two issues.   One issue was that the polymer? used to make the bits bind together when warm broke down fairly quickly which then essentially left you with the lower number which was usually not good for a hot hard working engine.  The other issue was that the lubrication properties of that polymer were not the best plus took up space that could be used for the real lubricant.  I believe that was also a down side to detergent oils, the detergents were not especially good lubricants and took up space.   A person (or engineer) had to weigh the pros and cons and make some tradeoffs to come up with what would work the best under most conditions and over time.  With the fairly current oils I don't think any of those are significant issues anymore so you might as well get the benefits of better flow on cold starts.   If you had to deal with and operate in freezing conditions I would say for sure go for the multi but since most of the cars in question here don't need to operate in those conditions it may be less of a problem so either will be fine.   

Another sign that the multis are getting better is the last small engine I bought (Briggs and Stratton) actually recommended 5w-30 full synthetic as preferred all weather oil.   They still had the full chart showing 30w and so on but as always these didn't cover the full range of possible temps for all climates.   

[76eldo]

Ask your mechanic if he is recommending a straight 30 Non Detergent oil.  Maybe he is worried about putting sludge in suspension in the oil passages.  I don't think they make multi viscosity non detergent.

Brian

[bullet bob]

He (mechanic) is in the process of dropping the tranny and replacing the seals, and noticed the blow-by tube had some residual oil in it. He felt that the "10" (10W30) was too thin for the engine and I should be running straight 30. I've always felt on the first start-up, your oil SHOULD be a little thinner. Hence, my question. Wanna run what's best. Again, thanks. BB

[Jon S]

Most mechanics today are clueless regarding the 1950's cars!  The blow by should have residual oil on it.  I've been using 10W/40 in the 1958 for over 40 years.  Straight weight oils are obsolete and have been replaced with significantly better lubricants.  Just DO NOT put synthetic oil in your engine.

[35-709]

Agreed, 10W-30 or even 10W-40 is just fine.

[Jay Friedman]

In my '49 331 motor I use 10W-30 in cold weather and 10W-40 in hot weather. 

[Mike Josephic CLC #3877]

The Cadillac Technical Service bulletins for the 331 engine recognized in 1955 that
the then "new" multi-grade oils, were approved for use.  In other words, using a
"straight weight" 30 HD in summer and a 20 HD weight in winter was no longer
necessary.

Use a 10W-30 weight OR 10W-40 year around with confidence and it will work fine for
you.  Stick to well know brands, API (American Petroleum Institute) approved brands,
which cover all the major brands out there.  Avoid bargain brands as they may not
have the proper additive package, an easy way to make a cheaper product.

Mike

[bullet bob]

Great information here guys. Appreciate all the replies. 10W30 it is. Thanks. BB

[P W Allen CLC# 20193]

Bob,

I've been using 20W 40 in my car for the past several years. I change it once a year. Oil on the stick is always nice and clean. I've been getting it from Classic Car Motor Oil. It already has plenty of zinc in it for the flat lifters. Works for me.

[Jay Friedman]

Paul,

Where do you buy it?

[35-709]

A Google search --- http://classiccarmotoroil.com/index.html 
Click on "Products"

Looks like they sell it direct.

Reading further at their site, the FAQs reveal this ---
Classic Car Motor Oil is sold by the case (12 quarts). The oil can be ordered from our website, www.classiccarmotoroil.com or by phone at (317) 225-0040. Classic Car Motor Oil can only be purchased through the Indiana Region of the Classic Car Club of America.

[Jon S]

Save your self some money and buy 10W/30 or 10W/40 Pennzoil or Quaker State and add 1/2 bottle (8 oz) of Red Line's Engine Oil Break In Additive.  Toy will have the correct ZDDP levels and great oil!

[35-709]

I run Mobil 1 15W-50 which has "enhanced" levels of ZDDP (reportedly 1300 PPM) in both my 472s.  I buy it at Walmart in 5 quart jugs which brings the price down to a reasonable (for me) level. 

[Jon S]

I run Mobil 1 15W-50 which has "enhanced" levels of ZDDP (reportedly 1300 PPM) in both my 472s.  I buy it at Walmart in 5 quart jugs which brings the price down to a reasonable (for me) level.

I would never run Synthetic oil in a classic car!  You're asking for leaks!

[35-709]

No leaks in mine.  Both are tight and have been on Mobil 1 since after break-in.  About 12,000 on the Caribou with an MTS engine and 22,000+ on the 472 in the '35.  Wouldn't run anything else anymore.

[TJ Hopland]

I have not found synthetic to leak (or burn) any worse than regular oil.  Stuff that leaks or burns synthetic still leaks and burns with regular oil.   Getting it at wally world is for sure a way to lessen the impact on the wallet if that is your issue with synthetics.   The last couple years I have been running a blend.  Price is good and I don't have to fully commit one way or another.   I also like that the blend gets you a wider range like a full synthetic does.   I'm running 5w-40 in just about everything I own.  Makes a big difference in the cool mornings and winters.

Another way to save money on oil is watch the parts store for sales.   Most of the big chains do a monthly special so you just have to wait for your brand to come around.  I was picking up the Napa brand full synthetic on sale for less than the regular price regular oil.  I think I still have a case and a half I bought for the daily driver I sold 2 years ago.  Wife's Mustang uses the same oil but with the miles she puts on that car its a several year supply.   

[dadscad]

I agree with TJ's analogy of oil usage. I've been using Amsoil full synthetic motor oil, transmission fluid and differential gear oil in my 63 since 2002, that's about 70K miles of driving. I have not found any negative issues, only benefits.

[gary griffin]

There is some confusion about multi grade oil. It is simple, they pass a test for the proper thickness at the higher temperature and the appropriate thinness at the lower temperature, according to standards.