With the cold snap here, I have been looking at various transmission fluids and their specifications as far as cold weather performance.
I drive a 1999 Malibu with a 4T60-E transmission, I believe, specced for Dexron-III. Last summer it was flushed and refilled with Esso Dexron-III/Mercon ATF. Never had transmission problems with it, and I found that once it got flushed the shifts were a lot firmer (at least until the first winter it went through) which was good. At that time it had 65,000 miles on it, and now it is up to a little over 80,000.
The Esso fluid has a viscosity of 37 cSt at 40 and 7.1 cSt at 100 which seems fairly standard, Brookfield viscosity of 17000 cP at -40, 8000 at -35, 3300 at -30 and 1000 at -20.
For comparison's sake I am looking at Mobil 1 Synthetic ATF and Petro-Canada Dexron VI ATF as the Mobil is rated as Dexron III, and the Dexron VI from Petro-Canada is what GM uses as factory fill and has back-specced for Dexron III and IIE applications.
I am wondering what exactly the Brookfield viscosity is and how it is measured. It seems from plain view that the Mobil 1 is rated at 5190 cP at -40, so does that mean at -40 it is less than 1/3 as thick as the Esso fluid I currently have in my transmission? Mobil doesn't list the specs of it at other temperatures, just -40. The Petro-Canada Dexron VI is 12030 cP at -40, 3184 at -30 and 1059 at -20, so comparable to the Esso fluid down to -30.
The Mobil 1 fluid has a viscosity of 7.6 cSt at 100 degrees and 34 at 40 degrees, and the Petro-Canada has a viscosity of 6.0 cSt (Mobil's Dexron VI synthetic blend is 5.83 and 29.5 at 40 degrees). I know Dexron VI is thinner, and the Mobil is thicker at operating temperature than what I am using and it looks like thicker overall through most of the normal range. The advantages of the thinner ATF according to GM is that it increases flow rate and allows for firmer shifting and a slight decrease in driveline loss for better mileage. What would the benefit, if any, of the thicker fluid be? Would it hurt the transmission using thinner fluid?
Both the M1 and Petro-Canada (which is a synthetic blend) have a flashpoint above 200 degrees C, the Esso is 180 degrees, but I never tow, and maybe twice a year get close to the GVWR rating of the car so transmission temperatures being high should not be an issue.
It looks like the M1 blows the Dexron VI I have seen from anyone to this point out of the water, and I am not really due for a fluid change, but considering it is -15 or lower four months of the year and that most of my driving is short trips, I am thinking about fuel mileage savings from the fluid which may actually be enough to pay for the change and the fact that I will be done servicing this transmission likely until I get rid of this car. Automatic transmissions are such a voodoo science that nobody wants to try anything that will hurt it.
I drive a 1999 Malibu with a 4T60-E transmission, I believe, specced for Dexron-III. Last summer it was flushed and refilled with Esso Dexron-III/Mercon ATF. Never had transmission problems with it, and I found that once it got flushed the shifts were a lot firmer (at least until the first winter it went through) which was good. At that time it had 65,000 miles on it, and now it is up to a little over 80,000.
The Esso fluid has a viscosity of 37 cSt at 40 and 7.1 cSt at 100 which seems fairly standard, Brookfield viscosity of 17000 cP at -40, 8000 at -35, 3300 at -30 and 1000 at -20.
For comparison's sake I am looking at Mobil 1 Synthetic ATF and Petro-Canada Dexron VI ATF as the Mobil is rated as Dexron III, and the Dexron VI from Petro-Canada is what GM uses as factory fill and has back-specced for Dexron III and IIE applications.
I am wondering what exactly the Brookfield viscosity is and how it is measured. It seems from plain view that the Mobil 1 is rated at 5190 cP at -40, so does that mean at -40 it is less than 1/3 as thick as the Esso fluid I currently have in my transmission? Mobil doesn't list the specs of it at other temperatures, just -40. The Petro-Canada Dexron VI is 12030 cP at -40, 3184 at -30 and 1059 at -20, so comparable to the Esso fluid down to -30.
The Mobil 1 fluid has a viscosity of 7.6 cSt at 100 degrees and 34 at 40 degrees, and the Petro-Canada has a viscosity of 6.0 cSt (Mobil's Dexron VI synthetic blend is 5.83 and 29.5 at 40 degrees). I know Dexron VI is thinner, and the Mobil is thicker at operating temperature than what I am using and it looks like thicker overall through most of the normal range. The advantages of the thinner ATF according to GM is that it increases flow rate and allows for firmer shifting and a slight decrease in driveline loss for better mileage. What would the benefit, if any, of the thicker fluid be? Would it hurt the transmission using thinner fluid?
Both the M1 and Petro-Canada (which is a synthetic blend) have a flashpoint above 200 degrees C, the Esso is 180 degrees, but I never tow, and maybe twice a year get close to the GVWR rating of the car so transmission temperatures being high should not be an issue.
It looks like the M1 blows the Dexron VI I have seen from anyone to this point out of the water, and I am not really due for a fluid change, but considering it is -15 or lower four months of the year and that most of my driving is short trips, I am thinking about fuel mileage savings from the fluid which may actually be enough to pay for the change and the fact that I will be done servicing this transmission likely until I get rid of this car. Automatic transmissions are such a voodoo science that nobody wants to try anything that will hurt it.
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