Schaeffer Blend 10w30 vs. 15w40

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Jul 4, 2002
Montgomery, AL
This may have been covered already but I just
noticed that the 10w30 and 15w40 blends are
almost equally capable in moderately cold weather.


CCS Viscosity @-25°C, cP (ASTM D-5293)

MRV Borderline Pumping Temperature °F
(ASTM D-3829)-28°to-30.22°


CCS Viscosity @ -25°C cP (ASTM D-5293)

MRV Borderline Pumping Test °F
(ASTM D-4684) -25°

I'm starting to think I can use either
down to -15 F with no adverse effects. Comments?

[ August 02, 2002, 01:13 AM: Message edited by: jjbula ]

Viscosity Grade Maximum Pumping Viscosity
25W 60,000 cP at -15°C (+5°F)
20W 60,000 cP at -20°C (-4°F)
15W 60,000 cP at -25°C (-13°F)
10W 60,000 cP at -30°C (-22°F)
5W 60,000 cP at -35°C (-31°F)
0W 60,000 cP at -40°C (-40°F)


Mini Rotary Viscosity
TP1, cP @-30°C (ASTM D-4684) 13,400


Mini-rotary Viscosity
TP.1 @-25°C cP (ASTM D-4684) 14,368
For that reason, in hot florida, I was wondering if it would be worth running in my 2002 Camaro 3.8L.

Being I live and sell here in hot florida, I can tell you that there is mmmmaaaannnnyyyy people running the schaeffers here and are finding it to work extremely well down here.

I have 5 people in an autozone just down the street from me that when it comes time for oil changes, they call me for oil instead of buying at a discount from their own store. They are just a very little few or the many that do that. Top ASE toyota master mechanics from regency toyota uses nothing but the schaeffers in all their toyotas and recommend it to some of their favorite clients.

Like I said before.... WAY too much is being put into just one aspect of any one oil and from that you can really nit pick every one to death and never come to any valid conclusions.

To point out, just because an oil has good pumpability doesn't actually effect it's operating viscosity since the VI's are dependant on heat and not the cold. So lower pourpoint means better flow IN THE COLD if you ever get in that situation, but down south in florida will that happen? I don't think so. Don't let yourself get caught up in such a way that you let one thing sidetrack you from the overall picture.
I'm trying to figure out what cP is actually
good enough at the coldest temps one will start
their car at. Are the gov tests at 60,000 cP good enough?

Why....I live in Alabama but visit family
in Chicago in Dec/Jan. I've gone before and
seen -10 or -20 F during my stay. perhaps the
short week of cold starts won't challenge an
engine on 15w40 too much.

I agree 5w30 is much better in that situation,
but is it really necessary if I have moly and
ZDDP in the oil? (i.e, good barrier lube)
The best plan is to change oil before the trip
but I don't like the idea of frequent oil

I would hate to be the guinea pig,
run an oil analysis and say
"I'll never do that again!"


Originally posted by jjbula:

Viscosity Grade Maximum Pumping Viscosity
20W 60,000 cP at -20°C (-4°F)
15W 60,000 cP at -25°C (-13°F)
10W 60,000 cP at -30°C (-22°F)
5W 60,000 cP at -35°C (-31°F)
0W 60,000 cP at -40°C (-40°F)

The schaeffers 10w30 works very well in those climates. I was in ST Loius during november with my car and it was very cold. My car sat for 2 and 3 days at a time with the 15w40 in it and when I came out and started it, it pumped up just fine. Yes, there was a slight momentary rattle at first due to the fact this engine isn't really designed for this heavy of an oil to start with but because of the barrier lube properties of this oil, I had no concerns and from the analysis I was correct. I have considered going back to a 10w30 but that will be next oil change if I do. It just depends on what I feel like that day as I don't worry about it because of the barrier additive. I don't recommend that to others and if your car is a small 4cly most likely it would be best to stay with the 10w30. As for chicago, not a problem with the 10w30. Besides, alabama gets cold too! at least up northern part.
My academic question about 15w40 seems to be useless.


With all the good wear readings on hard driven
vehicles on Mobil 1 5w30 I see that HTHS doesn't
need to be >3.5 to protect.

I still doubt the need for less than a 10w (synth) unless the wx is below -10F.
IMHO this viscosity thing is why M1 0W40 TS becoming ever more popular here even though **** near impossible to get. HTHS 3.6, VI 196, V cSt @100c 13.5. M1 5W50 is available everywhere here and they sell well lets just say lots. HTHS 4.4, VI 187, V cSt @100C 17.3. But if I was going to run a 5W50 I'd use Johnnys Performax 100 syn which I can still get.
We only have Castrol Syntec 5w50.

CAFE rules force Auto Manufacturers to insist the best oil for a car is the oil used for CAFE testing.

They are allowed to put one or two alternate grades in the owner's manual.

People mistake the oils in the owner's manual as the only oils suitable for use.

I don't think there will ever be a big enough market for 5w50 here.

[ August 02, 2002, 12:27 AM: Message edited by: jjbula ]
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