How to Determine the Correct Oil Grade for your Car
- Thread starter AEHaas
- Start date
Did someone say SAE 20?
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API SC ended in 1967.
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QR Code was invented in 1994. Curious if the Belgium 10W is still on the market and if that company makes the GC now?
what is the natural "hot rating" range of a 20W without vii? Can you formulate one to be a 40 or 50 grade for example? What would be the easiest or least expensive natural hot grade (no vm) to formulate?
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API SC is more of a back spec for engines from the late 60s, I believe when the API S-rating came about SD was the spec for current cars and they created the SA-SC speciation's for ranges of older cars though, for the model years SB and SC are specified the active specification at the time for gasoline engines was API MS (most-severe)
Caterham would not like low VI 0W16.
So i don't think the 10 psi per 1000 rpms applies to my old relic
10W30 in my 1996 Chevy C1500 4.3
60 lbs idling cold.
40 lbs idling hot.
50 lbs hot at 2000 rpms.
10W30 in my 1996 Chevy C1500 4.3
60 lbs idling cold.
40 lbs idling hot.
50 lbs hot at 2000 rpms.
It's not that a stock engine in a normally vehicle should follow those guidelines, it was a rule of thumb for minimum pressure needed in a SBC when you've got a hot sump in your racecar.
OVERKILL
$100 Site Donor 2021
Yes, and anything that might spec straight 10W is going to be older than 1967, hence the spec. Just like it's not uncommon to still see API SL or SM on some of the Euro lubes.
The hot rating will be whatever the base oil allows. If it's straight Group II for example it might be 20 or 30. Most 10w-30 PCMO's have VII in them as do 20w-50's, so I'd expect for the 20W you might be a 20W-20 or 20W-30.
The cheapest (which would be easy, given the API rating) would be straight Group I.
We look at J300 (thanks Widman!)
The only requirements for 20W are:
CCS/MRV and a KV100 of 5.6 or higher.
So, blend it with PAO and you are off to the races, but these will be blended "on the cheap", so they won't be using PAO.
Looking at Mobil's base oil portfolio, their EHC 65 product, which is Group II, would seem to fit the bill for an SAE 10W
CCS @ -20C: 3,100cP
KV100: 6.3-6.6
Noack: 10%
Pour Point: -18C
So that would give you a straight 10W-16.
That help?
Turbochargers don't generally need a ton of film strength. They just get hot.
Most definitely.
You have a knack for explaining complicated stuff in layman terms, which makes it easy for me, at least, to follow.
You have a knack for explaining complicated stuff in layman terms, which makes it easy for me, at least, to follow.
Good to see you back, Dr. Haas!
@OVERKILL
Thanks for the info!
Just to make sure I understand this correctly, based on J300 table, 20W Min cSt can be between 5.6 and 9.299 (< 9.3). Is that true?
if true, 9.3 also happens to be borderline Max hot rating cSt for 20 and 30 grades (i.e. it could be a very thick 20 or a thin 30) ... is that why you are saying 20W hot rating might be 20 or 30?
Q2:
was the 9.3 under the Min and Max cSt columns of Widman table by design or just a coincidence? What's the story behind it if any?
Thanks for the info!
Just to make sure I understand this correctly, based on J300 table, 20W Min cSt can be between 5.6 and 9.299 (< 9.3). Is that true?
if true, 9.3 also happens to be borderline Max hot rating cSt for 20 and 30 grades (i.e. it could be a very thick 20 or a thin 30) ... is that why you are saying 20W hot rating might be 20 or 30?
Q2:
was the 9.3 under the Min and Max cSt columns of Widman table by design or just a coincidence? What's the story behind it if any?
I though there was a rule that the W rating has to be based on the Min spec that the oil meets. For example you can't label a 5W as 10W. Maybe I am confusing the issues.
Can we theoretically have a 20W with 9.4 Min cSt (higher than 25W Min cSt) assuming it meets the ccs/mrv specs and there are no chemistry and/or formulation limitation?
^^^ The "W" and the non-W ratings have different J300 specs. Multi viscosity oils (ie, oils rated as xW-xx) need to meet the associated specs in both the "W" section and the non-W section of J300. If it's just rated "20W", then it only has to meet the 20W specs in J300.
Probably because the KV info on the "W" oils helps define the behavior of the oil better. But I agree, seems the low temperature spec requirements are most important.
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Here's an article on the history of SAE J300.
I was thinking if you design or formulate something (W) based on 2 primary parameters (ccs/mrv), why introduce another variable? However i can see that KV is at a fixed temp and maybe easier to relatively compare them ...
Wonder what's driving this table? I assume it was defined based on the existing base oils and formulation limitations ... Does the table get tweaked every few years or decades at least on the W side as the technology advaces?
Here's an article on the history of SAE J300.
good info! Thanks.
it may answer my last question. You posted it as I was typing.
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