API ratings

[aquariuscsm]

I was wondering,what`s the layman`s difference in these API ratings and what they mean:

Pennzoil 20W50 SM
Pennzoil GT 25W50 SG/CD
Royal Purple 20W50 CF/SJ
Valvoline 10W40/10W30 SM

 

[d00df00d]

Unfortunately, there really isn't a simple answer.

SM is a more recent spec than SJ, which is more recent than SG. More recent specs are usually tougher, but they also sometimes restrict the amount of certain kinds of additives, which may make them less suitable for certain kinds of engines (particularly older ones). In short, newer doesn't always mean better.

Use the SG in a car that calls for SG; SJ in a car that calls for SJ; etc. You can often swap grades around, but that's a good rule of thumb.

 

[qship1996]

Try finding some old SG or SJ rated oil on the shelf at your local autoparts store.....not going to happen.

 

[d00df00d]

Orly? How about this?

 

[qship1996]

It is a SM rated oil......and by design ok to use in all previous ratings.....kinda like dex 6 atf is also back specced for dex 3 and dex 2.

 

[ueberooo]

It's probably a big scam by the oil companies.

 

[d00df00d]

Originally Posted By: qship1996
It is a SM rated oil......

Royal Purple 20w-50 is API SJ, as the OP said.

http://eolcs.api.org/FindBrandByViscosity.asp?Viscosity=20W-50


You said this:
Originally Posted By: qship1996
Try finding some old SG or SJ rated oil on the shelf at your local autoparts store.....not going to happen.

I'm just saying that evidently it can happen, since Autozone carries at least one API SJ oil.

 

[ledslinger]

Is a fresh made (not old stock) SG or SJ oil good to use in engines with a later rating such as SL or SM? Is there more risk of damaging the cat converter?

How would these oils differ from an SL or SM oils? Mostly higher ZDDP levels?

 

[d00df00d]

Originally Posted By: ledslinger
Is a fresh made (not old stock) SG or SJ oil

Yes.

Originally Posted By: ledslinger
good to use in engines with a later rating such as SL or SM?

Perhaps. Depends on the engine. It's probably not better than using an oil that matches what the engine calls for.


Originally Posted By: ledslinger
Is there more risk of damaging the cat converter?

Yes. How much more is another question.

Originally Posted By: ledslinger
How would these oils differ from an SL or SM oils? Mostly higher ZDDP levels?

Probably. It's best to ask the manufacturer though because it may vary from one case to another.

 

[ledslinger]

I suppose a better question is a newly made SG or SJ oil lacking in any area for an engine that specs SL or SM?

 

[d00df00d]

It may be, since those are older and less strict specs. However, it's also possible that those oils WOULD meet SL or SM but for one or two details that only matter for certain kinds of applications. Again, it depends on the oil and the application.

 

[qship1996]

yes

 

[ledslinger]

Don't manufacturers who currently make older spec oils do so to make them stouter, and not to scrimp on additives?

I'm talking name brands, not cheapies like Cook's other grocery store oils.

 

[d00df00d]

Basically. Or, they could be doing it to save money because they intend their oil to be used only for certain kinds of cars.

"Stouter" can mean different things in different cases, and there are many different kinds of additives to skimp or not skimp on. The point is that the additive packages are matched to the metallurgies and designs of engines with matching specs. This usually means lots of ZDDP, for example.

A modern engine, by contrast, might want a different mix; perhaps it doesn't need as much ZDDP but would love an oil with highly resilient base stocks, say for deposit control and oxidation resistance. Modern turbo engines come to mind. Thus, "stoutness" for those engines means something different.

An API SM oil might be considered "weak" for old engines but "stout" for new ones; the opposite may be true of an SJ oil.

 

[ledslinger]

I bought a bunch of BRP SeaDoo oil that is also for motorcycles. The 5W-40 synth is SG, and the 10W-40 conventional is SJ. I planned to use this in motorcycles but now have other oil for this and am considering using it in a few of my cars. The cars in question are older (pre 2001)and don't call for SL or SM and are for SJ or lower. I am verifying these oils aren't missing anything that SL or SM oils have.

I have read (internet, has to be true) that these BRP oils are close to Castrol Syntec and GTX.

 

[ledslinger]

I looked at the BRP oil bottles and the 10W-40 conventional says SJ SH or SL, so I'm good to go with it. The SG 5W-40 is what I would more like to use.

 

[Hokiefyd]

Aren't newer API specifications tougher on sludging and deposit control? I would think an older motor oil would be inferior in that area.

 

[ledslinger]

Most motorcycle oils are SG or SJ. I don't know if they lack in any of these areas.

 

[aquariuscsm]

I`m curious as to which of these oils are the best at protecting a car that is driven fast and hard:

Pennzoil GT 25W50 API SG/CD
Pennzoil yellow bottle 20W50 API SM
Royal Purple 20W50 API CF/SJ

Seems the Aussies like the 25W50 grade. Pennzoil Australian site recommends 15W40,20W50,25W50 for my car. And I drive my car the way it`s meant to be driven,but it`s NEVER EVER abused.

 

[ueberooo]

Regarding the ZDDP, my solution is to throw in 1.3 ounces of Lucas Break In additive (available for cheap in bulk via amazon--free shipping too if you order two 16 oz bottles). Assuming the car's oil capacity is about a gallon, this kicks up the Zinc levels about 300 ppms which, IMO is just what you need for the new oils. I wouldn't go over raising over 450 ppms though, because the added wear protection would be minimal and (esp if you car burns oil) the wear on the cats would be a concern.