10w40 dino oil to what weight synthetic

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651
Location
la jolla, ca
hey guys i have a 94 Z28 LT1 camaro that i just sold but am looking at picking up another LT1 (was tired of the auto and really wanted a 6-spd) but anyway i was using 10w40 in my LT1 usually castrol gtx or valvoline but wanted to know if mobil 1 had a 10w40 or if not what would be a similar weight to go to? i live in so. cal so my car never sees below 40's most commonly 50-80's temp wise. thanks for any help
 

windnsea00

Thread starter
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651
Location
la jolla, ca
i was just recommended to use a 40 weight since of the higher mileage on my car and since commonly camaros are driven hard plus we have large engines w/ large clearances (350ci)
 
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1,488
Location
Los Angeles
If you insist on Mobile 1, they do make a 10w-40. However, I do not know how shear stable it is. Mobile also makes a 0w-40. It is a light 40 weight oil. You might want to try it as well. A better choice might be German made Castrol 0w-30. It is a heavy 30 weight and cost about the same as Mobile 1.
 

Patman

Staff member
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21,993
Location
Oakville, Ontario
I'm running German Castrol Syntec 0w30 in my LT1 (in my 95 Formula) and my first oil analysis on it looked extremely good! This oil is a thick 30wt, almost a 40wt, and the LT1 likes that. Mine is approaching 100k now, and still runs very strong (best ET last year when it was still bone stock was 13.74 at 100mph!), so the LT1 (as you already probably know) is one very durable engine!
 
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2,480
I think if you wish to get a rough 10-40 conversion to synthetic you'd be looking at either a 0-40 or 5-40. A 5-50 wouldn't be a bad recommendation either. I think Castrol Syntec comes in a 10-40 too...
 

Patman

Staff member
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21,993
Location
Oakville, Ontario
quote:
Originally posted by Dr. T: I think if you wish to get a rough 10-40 conversion to synthetic you'd be looking at either a 0-40 or 5-40. A 5-50 wouldn't be a bad recommendation either. I think Castrol Syntec comes in a 10-40 too...
It does in the US, although I've never seen it in Canada. Actually there are no 10w40 synthetics for sale up here in Walmart or Canadian Tire. No 5w40 or 0w40 for that matter either. You have to go to specialty shops to find those viscosities.
 
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526
Location
Manitoba Canada
Are you comparing kinematic viscosities at moderate shear rates (ASTM D445), or are you comparing High Temperature High Shear rates (ASTM D4683)? Two oils that have very similar kinematic viscosities at moderate shear, say 14.1 cSt and 14.3 cSt, may behave entirely different at HTHS (One million shears at 150 C): say 3.9 mPa s and 3.1 mPa s. A 10W-40 and 10W-30 regular oil are refined from the same light 10W base stock, with polymeric additives to "build" the viscosity at operating temp. You have to watch out for excessive cross-grading of conventional oils, which implies heavy polymer content. When exposed to a HTHS environment, you can expect permanent viscosity loss. The Mobil 1 0W-40 is considered a "light duty" 40 and folks here have commented on its somewhat questionable HTHS values: 3.6 mPa s @ 150 C for VOA. At the same time, it's factory-fill in Porsche, BMW, and Mercedes cars, so it can't be that bad. Mobil Delvac 1 5W-40 is a HD diesel oil cross-graded to API SL for gasoline engines. It has excellent HTHS stability ranging from 3.9-4.0 mPa s @ 150 C and can handle a lot of trash in the oil. If you're really worried about HTHS protection, perhaps you shouldn't be looking at a xW-40 anyway. Mobil 1 15W-50 is easy to find and appears to have the best additive package of all the Mobil 1 grades. In so cal I don't think you have to worry about MRV BPT too much. Mobil 1 15W-50 has a kinematic of around 17.4 cSt @ 100 C, with a HTHS of 5.11 mPa s @ 150 C. These are VOA values.
 

Patman

Staff member
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21,993
Location
Oakville, Ontario
quote:
Originally posted by Patman: No 5w40 or 0w40 for that matter either. You have to go to specialty shops to find those viscosities.
[Bang Head] I must've had a brain fart when I posted that, since we can get Delvac 1 5w40 up here at Walmart, and some Canadian Tire stores carry 0w40 Rotella T synthetic. But still no synthetic 10w40s though.
 
Messages
526
Location
Manitoba Canada
quote:
Originally posted by Patman:
quote:
Originally posted by Patman: No 5w40 or 0w40 for that matter either. You have to go to specialty shops to find those viscosities.
[Bang Head] I must've had a brain fart when I posted that,

Heck, I get those ALL THE TIME! Don't worry about it. Jerry
 
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2,768
Location
Tn
I fail to see the purpose of 10W-40 in synthetic or conventional. Why?? [I dont know] No 10W-40 conventionals for me. [SPAZ!] Can't see it in Syn either.
 
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1,837
Location
Pac NW
Amsoil 100% Synthetic 10W-40 AMO is, IMHO, one of the finest oils available, period. (PERIOD!) [LOL!] A little $pendy, but way good enough for my ol' ZX-11. [Burnout] Winter, summer, gas, diesel, extended drains, etc. What is not to like about this product if 10W-40 is the proper vis for your vehicle? [Cheers!]
 
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2,768
Location
Tn
True Norm, but it is a kinda specialty oil. I was thinking about passenger car only. The 0-30 ain't bad either. I'm just skeptical that anything more than a 30 wt. is needed to get the job done in most cars running today. I have a hard time with the euro specs.
 
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