I was thinking how we could up the hp in our FX's when I remembered a clip from Hot Rod TV. They drained the engine oil, trans fluid and differential fluid from a Ford. The fluids were replaced with Royal Purple synthetics. They dynoed it afterward and it gained some ponies. There are numerous articles from various magazines at their website royalpurple.com showing hp and mileage gains from various foreign and domestic cars. Less friction = more hp.
I just changed over to Mobil 1, but am planning to use their diff oil soon. Looks very easy to change the diff oil. The pumpkin has two plugs, one to drain and one to fill, so it's a no brainer. All you need is a 3/8 ratchet to get the plugs out. Going to stay away from changing the trans fluid, too expensive of a item to not be covered by warranty if it were to take a puke. Since our FX's have a IRS there will probably be a smaller gain in hp than if we had a solid rear axle since the wheel bearings are isolated from the diff, but I think it's worth a try.
Stock takes 80W90 oil, Royal Purple only makes a 75W90 that will be compatable.
If you plan on doing this there is no capacity available, but the pumpkin is small so I'm guessing that one quart will be enough. When filling the diff up, fill to just under the fill hole. Just stick your finger or a screwdriver in there to see how much it is full, put the plug back fill plug back in, (of course you put the drain plug in before filling) :wink: and you're done.
I'm a mechanic, not very familiar with foreign makes, but have learned much from reading at this hellacool website.
I just changed over to Mobil 1, but am planning to use their diff oil soon. Looks very easy to change the diff oil. The pumpkin has two plugs, one to drain and one to fill, so it's a no brainer. All you need is a 3/8 ratchet to get the plugs out. Going to stay away from changing the trans fluid, too expensive of a item to not be covered by warranty if it were to take a puke. Since our FX's have a IRS there will probably be a smaller gain in hp than if we had a solid rear axle since the wheel bearings are isolated from the diff, but I think it's worth a try.
Stock takes 80W90 oil, Royal Purple only makes a 75W90 that will be compatable.
If you plan on doing this there is no capacity available, but the pumpkin is small so I'm guessing that one quart will be enough. When filling the diff up, fill to just under the fill hole. Just stick your finger or a screwdriver in there to see how much it is full, put the plug back fill plug back in, (of course you put the drain plug in before filling) :wink: and you're done.
I'm a mechanic, not very familiar with foreign makes, but have learned much from reading at this hellacool website.
