Oil classification
 

Hello everybody,



can someone please tell me the API or SAE classification for an oil that is labeled "30 - 40 Weight" in the USA?



Thank you in advance.

Re: Oil classification
 

30 weight or 40 weight oil has VISCOSITY of SAE 30 or SAE 40. It says nothing about the API classification.

To understand this, you really need to read for yourself.

API: http://www.pqiamerica.com/apiserviceclass.htm

SAE oil viscosity: https://www.jcmotors.com/images/unde..._viscosity.pdf

.

Re: Oil classification
 

Hello Jim,


thank you for yout helpin' answer. That was what I want to know, the viscosity.

Re: Oil classification
 

I did not understand the word "weight" correctly. Weight means for me a weight, z. kg or lb etc.

If I understand correctly, is here in this case the vocabulary "Weight" equal to the viscosity?



Example "Weight 10" = SAE 10. "Weight 50" = SAE 50.

Re: Oil classification
 

The oil industry uses the words "Light" and "Heavy" to describe viscosity, Saudi Light or West Texas heavy to describe crude oils. Each crude is different as it comes out of the ground. This is used through out the industry. Light oils are thinner and pour easier. Heavy oils are thicker and can not be poured as easily
I hope this helps.
Terry

Re: Oil classification
 

I may be wrong, but I don’t think his question is about “crude” oil, but rather he’s concerned with the viscosity of oil he may put in his crankcase.

Re: Oil classification
 

Yes you are correct in you understanding.
Mike

Re: Oil classification
 

Yes, but I was trying to show the origins of the designations "light and heavy" The crude oils were called by these terms and the designations carried over into the refined products too. The light oils pour easily and the heavy oils don't, whether as crude or refined. Sorry I didn't make that clear. In Germany, they use DM (?) specs on everything. It's like our ASE or API but I don't how they grade oils, so I don't know exactly what numbers he's dealing with. Their 30 wt may be equivalent to our 90 wt or it may be the same. I don't know!
Terry

Re: Oil classification
 

Many thanks for all these helpfull answers!


My question arose because the Stipe shock absorbers instructions wrote "Use Oil Weight 30 or 40".



I know a lot about lubrication, because that was my job. But the US name "weight" instead of "SAE" was previously unknown to me.



Here car oils are always marked according to SAE and API. SAE 10 - 60 for car engine oils. From SAE 70 - 140 gear oils. Then there are also multigrade oils. 5W-40 is the universal oil. But there are also very thin 0W-30 oils or very long-splayed 10W-60.



An infinite material to discuss! I drive in all vehicles only synthetic esters, which burn almost without residue.

Re: Oil classification
 

Yes, Werner, you are correct. This is odd, old, terminology. English can be very unpredictable.

.

Re: Oil classification
 

Werner, The word "Weight" is incorrect! The 'W' used in "20W" or "30W" means "Winter", NOT "Weight"!
Years ago oil viscosity was just 10, 20, 30, 40, 50. As refining methods improved 10W, 20W, 30W, etc. became available. A 'W' (or Winter) oil has a lower pour point. So a 20 and a 20W oil have the same viscosity when hot (typically 212 F. or 100 C.) but, the 20W oil is 'thinner' (flows better) at low temperatures.
Here's a quote from "machinerylubrication.com": "the 'W' designation..is used to denote oils that are suitable for use at colder temperatures". And, "The winter (W) group measures the cold-cranking and pumping ability of oil temperatures as low as minus 10C. to minus 40C.".
This is just a brief comment. A lot more detailed explanations are on that website.
Just remember, it's Winter, not Weight!

Re: Oil classification
 

When it comes to multi-weight oils, 10W40, This oil has the viscosity of a 10 weight and the film strength of a 40 weight.

Re: Oil classification
 

Hello Patrick,

that is misleading. SAE 10W-40 means that the oil when cold flows like a SAE 10W (winter) single-grade oil and -40 means that it flows in the hot engine like a thick (summer) SAE 40 single-grade oil.

Re: Oil classification
 

The correct term is "multi-viscosity" oil, not "multi-weight". n The 'W' stands for "Winter", not 'weight'.