When did 5w spec change?

[n8wvi]

I seem to recall reading that a couple years back the 5w spec [and probably others] changed to become more stringent. Anybody know more details? Like what were the changes and when was the change made? Kinda makes it confusing for a consumer w/ an older vehicle. Even my '97. Think about it. If the mfgr says to use 5w-30, then the spec changes, maybe all the 10w oils of today would pass the 5w spec of 'yesterday'?

Thanks,
Dave

 

[Big Jim]

Perhaps you are refering to the periodic upgrade that all oil goes through with the API grading system. One of the upgrades was last year. The upgrades come about every four or five years. The latest API rating is SM, and the prior one was SL.

I'm not aware of any other rating change or of any that are particular to 5W oil. Does anyone else have an answer here?

 

[427Z06]

As of December of 1999 the physical requirements listed on the SAE J300 (a table listing the requirements for different viscosity grade classifications) have changed for the CCS test. The testing procedure has not changed, just the specs required to meet certain viscosity classifications.

The CCS testing temperature has dropped by 5 degrees C for each "W" classification. In addition, the cP max value has basically doubled. (In other words, kinda' of a wash for dinos)

This change was introduced by the SAE to reflect changes in current automobiles. Present day engines will turn over at lower temperatures with higher viscosity grade oils than engines of the past. As a result, since automakers use the J300 to determine which viscosity grades should be used in their vehicles, the specs needed to be updated to reflect new engine technology.

Low Temperature Pumping Viscosity with No Yield Stress did not change.

[ March 18, 2006, 07:58 PM: Message edited by: 427Z06 ]

 

[n8wvi]

thanks 427, I think that's what I was looking for. But if the maximum cP doubled, and the temp dropped 5 degrees C, what was the point of the change??? It sounds like a 5w from '96 is the same as a 5w from now, same w/ 10w.

Dave

 

[bruce381]

makes the test more severe or real life since oils that had marginally passed in field service failed so test was notched up in severity.
bruce

 

[427Z06]

bruce381 nailed it. Good(cold temp performance) dinos would roughly double given the change. Not so good ones, would more than double and fail, reflecting real world results.