What would be the harm of not useing the synthic type rear end lube in the same viscosity. Have heard some people on here say they have done it. Its a little cheaper. I have the 3.73 LS, and i would have to put in the friction modifier.
I was just wondering. I know that Ford puts in synthetic so it doesnt have to be serviced for 100,000 miles. But if the regular lube is the same weight and viscosity whats the difference except you will have to service it at 25000-30000 miles? I would rather do that and save a few bucks and actually have to look at the rear end every 2 years than just say its good for 100,000 miles. Just curious.
Im not ready to do it yet, just looking around at what others have done and seen that some others use regular lube instead of syn.
synthetic = a little bit "slippier", less viscous, less affected by heat and cold. maintains it's properties better.
I'd just spend the few more $$$ and get the synthetic. You get more benefits with it, and it can also affect MPG's. the Synthetic is slippier (real word?) and will cause less parasitic drag, but still adequately lubricate the diff
Another thing to consider there is no such thing as a non-syn 75w140 the closest is 85w140. IMO even in a warm climate i would want the thinner fluid when you first start driving the price difference isn't much especially since the diff fluid dont get changed often
The 85w140 really does not work good with the stock l/s . I would say maybe if it was just an open diff. Ford has been using only synthetic in the sterling axles for the last 15 years. You said it yourself you are going to look at it every two years. So I would spend the extra 21.00 now and by the time you do it again in two years the cost is small. You can also get mobil 1 75w140 on sale at Autozone right now for 9.99 a quart.
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If it doesn't fit, FORCE it.
If it breaks, well, it needed replacing anyway.
Ok thanks guys, i figured something out also, i dont know why i had it in my head that the bottle the rear end lube comes in were pints and i was thinking i had to get 6 of those bottles, but it just hit me that they are quarts and i only need three. Thats why i was wondering about cost. So i will just do the synthetic. Thanks again guys.
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