Going to work on doing my 100k service on the F150 this summer and one of the jobs is the front dif. I'm sure its in just as bad of need as the transfer case was. Spec is 80w90, I think I'll go with the 75w90 synthetic alternative but I'm a little torn on which one to get. Motorcraft and Amsoil run about the same price but I can save some money going with SynPower or M1 which are also about the same price as eachother and a couple bucks less per quart than Amsoil.
In the past I've had no troubles with Synpower. I did have some wheel bearing issues on my Mustang after switching to M1 which I cannot rightly explain as levels were fine and mileage wasn't too excessive at that time. Is there any real difference between the two? I have to imagine both are using grp III+ these days, and both seem highly reputed. Truck seems most 4WD action in the cold of winter so I do think the 75w will be a slight advantage.
Addendum: Looks like M1 is very slightly less impressive on paper.
SynPower:
VI: 150
PP: -48C
Vis 100C: 15.6
Vis 40C: 100
M1:
VI: 146
PP: -39C
Vis 100C: 14.6
Vis 40C: 103
I know numbers are FAR from the whole story but it seems the SynPower is marginally superior?
In the past I've had no troubles with Synpower. I did have some wheel bearing issues on my Mustang after switching to M1 which I cannot rightly explain as levels were fine and mileage wasn't too excessive at that time. Is there any real difference between the two? I have to imagine both are using grp III+ these days, and both seem highly reputed. Truck seems most 4WD action in the cold of winter so I do think the 75w will be a slight advantage.
Addendum: Looks like M1 is very slightly less impressive on paper.
SynPower:
VI: 150
PP: -48C
Vis 100C: 15.6
Vis 40C: 100
M1:
VI: 146
PP: -39C
Vis 100C: 14.6
Vis 40C: 103
I know numbers are FAR from the whole story but it seems the SynPower is marginally superior?
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