Pennzoil ?

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Looking at a nos can of Pennzoil straight 30 and it says "service ML-MM" any ideas what these letters mean ?
 
That's old school API oil labeling. They went obsolete back in about '72.

ML = Motor Light
MM = Motor Medium
MS = Motor Severe
 
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The only information I was able to find through research states the following:


ML = "motor light" oil

The other text seems to refer to viscosity.
MM = apparently considered "regular" oil
MS = premium/heavy duty oil

Apparently all of these were early API classifications.
 
Thanks a lot, that clears things up. Now the next question would be, if the cans look good, no rust, stored in a cool dry building, would it bo ok to use ?
 
So iyo simply no chance at all ? There a more than a few cans of it, for super cheep. I wonder if Blackstone could do an oil analisis of unused oil and tell me if it's ok ? I know they can test used oil but I've never asked them about new old stock.
 
They can test dated oil like that, for sure. If it were me, I'd have it tested rather than use it. The entertainment and educational value of a VOA on an oil like that would be of far greater worth than actually using the stuff.

Maybe it's just me, but I'm more curious as to what's in it rather than seeing how it performs when there are much more modern products readily available without breaking the bank.
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I agree, for the money a test cost it would be worth it to see just what really is in it and if it's ok to use. There are 6 cases of oil, all Pennzoil 30wt. $10 a case hard to pass on. $60 wouldn't be too hard a hit if it was bad & I haven't even tryed to talk him down some, maybe tell him $25 to test it and see if he will knock that much off ? All comes down to the gamble. Just think though, if it's still good what a score !
 
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The real issue isn't so much if it's "still good." It may very well be within specifications and in a serviceable condition. But serviceable for what? Even if one still had an engine where this oil met the specifications, there are certainly better options available now. I've only used a monograde once in my life and that was to use up a stash, and it met the requirements, of course. That was around thirty years ago, though. As it was, I had to do some fast, logical talking with reference to the owner's manual to avoid a paddling from my dad, who was quite annoyed that I ignored the perfectly good multigrade 10w-30 in the shop.

Given the vintage of the oil, it was probably worth less than $10 a case brand new.
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What do you have that could actually make use of the oil?
 
I rebuild small engines, Kohler, Wisconsin, etc. Mostly the older stuff.So I can put it to good use.
 
Ok , for what its worth , even a MS rated oil wouldn't meet the needs of a modern single cylinder engine of today.
If your rebuilding 40+ year old engines , maybe , though you would be much better off using a modern oil in these engines.
 
As Skellyman points out, the odds are that you're going to be better off with a modern oil. Now, if this stuff had really high levels of ZDDP or something like that, it might be great on some of the old, old stuff. But, I doubt it's going to have any more ZDDP than a modern PCMO.

On the other hand, even the average modern single cylinder motor isn't going to be all that picky about oil, even though the manual will tend to call for the latest specifications. If you were up here and concerned about price, I'd send you to WM for a 5 gallon pail of SN rated straight 30, and you'd be set.
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I have a little story you would appreciate, given that you rebuild small engines. Around twenty years ago, I'm guessing, my dad and I had finished either seeding or harvesting at the farm, and we're about done getting everything put back. In the stereotypical farm graveyard of old cars and OPE, there was an ancient, small grain auger (guessing from the 1940s) that had been sitting there for at least twenty years. It was simply too short for modern grain trucks, much less modern grain bins.

He decided he wanted to get it going. I'm guessing it was a B&S, from what I remember of the design. Well, we pulled the plug and gave it a brushing. The gas tank came off for a cleaning. Fresh gas was dumped in, along with a fresh fill of QS 10w-30. A few pulls later, and it was running.

Let a modern single cylinder sit outside for 20+ years and see how that goes. Most people have more trouble with the small engines they use yearly.
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Cool story. To be ohnest the late model tecumseh ohv motors could use a good dose of zddp. I see a lot of top end wear in those engines, paticularly in the push rods. In the last say ? 8 years or so imo the wrong oils have been hurting the older Kohler, Wisconsin, Onan, etc. engines. One wouldn't think with such light valve spring psi it would not make all that much difference but I see no other explanation for some of the cam, followers and valves and guides I've been throwing in the trash. Valve tip wear is also getting out of hand, I don't know how many times I've had to get in there with a die grinder and cartridge roll and cut the mushroom off the tip just to remove the valve. Don't get me wrong, by no means it's not and epidemic and cams aren't wearing flat, just excessive wear with sharp wear patterns over the lobes nose and strange looking wear patterns on the ramps. It has come down to I now tell all customers to be prepaired to buy a set. On the other hand who knows the maintence the motor had or didn't have and just what kind of oils have been used in the past in any given old engine ?
Cylinder & piston wear is a whole other story. It's hard to make an assumption on most all of the cylinders I've ran a bore gauge through because so many backyard engine rebuilders rering and use those junk spring loaded hones through them, resulting in more bad than good & once again who knows if the piston was replaced and just what tho old one looked like before someone with limited knowledge fudged the whole mess.
The bottom line is people should know ( and I do tell them ) whats what and what they need before changing oil. Funny how pople seem to listen a little better after they pay a bill like that.
 
Exactly. I think the maintenance that people perform on their OPE is lacking, too. We can point to lower ZDDP content and cheaper materials, but those aren't the only issues.

Maybe people should just use HDEO or Valvoline VR-1.
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I know I've got an old bottle of Castrol Syntec 5w-50 in my snowblower right now.
 
Originally Posted By: AandPDan
That's old school API oil labeling. They went obsolete back in about '72.

ML = Motor Light
MM = Motor Medium
MS = Motor Severe


I think I remember reading in an old seventies manual that ML became SA, MM became SB, and MS became SC when the current A.P.I. "service" [then "spark"] categories came out.

Maybe you could maybe mix it 50/50 with moly grease to make an ersatz engine assembly lube, it would probably be fine for break-in.
 
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