Chevron supreme straight weights

Messages
263
Location
DFW, TX
AFter reading a bit here about Chevron, I went to their spec sheets. I was floored at the specs for their straight weight oils. I know most here say that straight weights have no place anymore, but check this out:
code:
             10w30    10w40   20w50   30     40
[email protected]      73.5     104     176    82     128
[email protected]     10.8     14.8    19.0  10.3   14.0

These look like some serious (and inexpensive) oils for the hot summer climates. I bet that straight 40 could qualify as a 20W40 if they wanted. Heck, I would feel save with the 30wt in my car for a Dallas winter. After all, my service manual says I could run a 20w40 when temps are 20+ F.
 
Messages
1,357
Location
California, USA
The only problem with this is that 40C is over 100F. Without listing the pour point, you don't know at what temperature it stops flowing. This test is just used to calculate the viscosity index. Castrol lists a minimum recommended temperature of 40F for SAE 30 and 60F for SAE 40 right on the bottle. The main advantage I see in straight grades is the lack of VI improver additives, meaning it will not "shear" to a lower grade in use. They also tend to have higher flash points, lower volatility and better oxidation stablilty. I have used them very sucessfully in the summer to reduce leakage and smoke in older engines.
 
Messages
453
Location
Galveston, TX
quote:
Originally posted by Chris A: AFter reading a bit here about Chevron, I went to their spec sheets. I was floored at the specs for their straight weight oils. I know most here say that straight weights have no place anymore, but check this out:
code:
             10w30    10w40   20w50   30     40
[email protected]      73.5     104     176    82     128
[email protected]     10.8     14.8    19.0  10.3   14.0

These look like some serious (and inexpensive) oils for the hot summer climates. I bet that straight 40 could qualify as a 20W40 if they wanted. Heck, I would feel save with the 30wt in my car for a Dallas winter. After all, my service manual says I could run a 20w40 when temps are 20+ F.

I use straight-weight mineral oil (Castrol HD-30) all the time in Gulf States hot weather. But it drives the "Powers that Be" crazy. People keep telling me straight weight is no good, nobody uses it any more, blah blah. But I say, straight weight does not shear down as much in brutally hot conditions. At 3,000 miles, my straight weight is pretty much the same viscosity. My buddy's multi-grade 10w-30, though, has gone to the dogs by 3,000 miles. This is in hot Summer weather.
 
Messages
8,937
Location
SC
quote:
Originally posted by Flimflam: I use straight-weight mineral oil (Castrol HD-30) all the time in Gulf States hot weather. But it drives the "Powers that Be" crazy. People keep telling me straight weight is no good, nobody uses it any more, blah blah. But I say, straight weight does not shear down as much in brutally hot conditions. At 3,000 miles, my straight weight is pretty much the same viscosity. My buddy's multi-grade 10w-30, though, has gone to the dogs by 3,000 miles. This is in hot Summer weather.
I'm just curious: How do you know your vis hasn't changed and that your buddy's has. Have you done oil analysis on your oil and your buddy's oil to determine that?
 

Chris A

Thread starter
Messages
263
Location
DFW, TX
I don't think the pour point is very important. It is the viscosity at different temps which matters. But, since you mentioned it, the pour point is -27f/-22f for the 30/40 respectively. The viscosity of an oil can be drawn on log paper and is a straight line. I have drawn these two oils against Mobil dino oils and the 40 is always thinner than the Mobil 20W50 above 10f. I'd bet the 30 wt is always thinner than most 15W40 above 10f, but I haven't plotted a 15w40 oil yet. I plan on running the 40wt this summer and may end up running the 30wt over next winter. I agree that this oil is not for every car, but for an engine that burns some oil, it may be a good choice.
 
Messages
453
Location
Galveston, TX
quote:
Originally posted by G-Man II:
quote:
Originally posted by Flimflam: I use straight-weight mineral oil (Castrol HD-30) all the time in Gulf States hot weather. But it drives the "Powers that Be" crazy. People keep telling me straight weight is no good, nobody uses it any more, blah blah. But I say, straight weight does not shear down as much in brutally hot conditions. At 3,000 miles, my straight weight is pretty much the same viscosity. My buddy's multi-grade 10w-30, though, has gone to the dogs by 3,000 miles. This is in hot Summer weather.
I'm just curious: How do you know your vis hasn't changed and that your buddy's has. Have you done oil analysis on your oil and your buddy's oil to determine that?

(1)Look and feel test. Hot engine, pull dipstick. If oil is too runny, it is no good. (2)Oil pressure gauge. Shows inability to maintain pressure in extended driving under very hot conditions: means oil is no good. You will probably laugh at the imprecise oil evaluation. But sometimes, on a long, say TX-to-NY haul, you have to have ability to make a snap decision to dump all the motor oil out and have a new shot of fresh oil thrown in. Waiting for the lab test results means a dead engine by the time the test results are in.
 
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