I changed out my stock gear oil with Royal Purple GearMax 75-140W on my '06 GT. It took about 2.5 bottles which it should; I filled it until it ran out fill hole. The new seal is solid on diff cover. Now I notice a whine, especially in 4th and fifth @ 2000 rpm. It appears to be more audible when cold, but definately more whine then when stock fluid. Can anyone suggest why this is, or has anyone experienced this problem. This stuff if supposed to quiet gears, but it did just the opposite. I did not add friction modifier because RP says it's not needed. Thanks for any replys or suggestions.
I changed out my stock gear oil with Royal Purple GearMax 75-140W on my '06 GT. It took about 2.5 bottles which it should; I filled it until it ran out fill hole. The new seal is solid on diff cover. Now I notice a whine, especially in 4th and fifth @ 2000 rpm. It appears to be more audible when cold, but definately more whine then when stock fluid. Can anyone suggest why this is, or has anyone experienced this problem. This stuff if supposed to quiet gears, but it did just the opposite. I did not add friction modifier because RP says it's not needed. Thanks for any replys or suggestions.
Add 4oz of Ford or Amsoil friction modifier anyway.
I didn't add any when switching to RP. What does it do?
Mainly for the trac-loc to ensure the clutch packs are lubed properly so they don't bind on slow turns. But it will help to quiet the gears a little too (unless you add too much in which case it may actually do the opposite).
Even Amsoil says you don't need it with their synthetic lube.
There are a lot of mfg that say that. But even the Amsoil tech documentation says to add their friction modifier if the clutch packs starting making noise.
Add 4oz of Ford or Amsoil friction modifier anyway.
I tried adding the friction modifier, but still had whine. Finally, I drained all R/P gear fluid, cleaned gears good with brake cleaner and went back to stock Motorcraft 75-140W gear oil with 4 oz. of friction modifier. NOW it's nice and quiet, like it was with original fluid. I just hope the Royal Purple Motor Oil performs as advertised, I plan on sticking with it.
I tried adding the friction modifier, but still had whine. Finally, I drained all R/P gear fluid, cleaned gears good with brake cleaner and went back to stock Motorcraft 75-140W gear oil with 4 oz. of friction modifier. NOW it's nice and quiet, like it was with original fluid. I just hope the Royal Purple Motor Oil performs as advertised, I plan on sticking with it.
So, the moral is the stock gears don't like royal purple gear oil? I don't get it
I believe there is a TSB concerning gear whine. Check it out.
TSB06-19-2. I just had this done last week. I had what I would describe as a howl when making U-turns. Unfortunately you are probably SOL as far as having your warranty cover this since you modified it by putting in the Royal Purple oil. I would dump it, put the Ford lube back in and then take it to the dealer. I wouldn't even think of changing my axle or trans fluid to one of the miracle synthetics. I went through that fiasco when I had my 94 Supra Turbo. At that time many of us put Redline in the Getrag 6-speed trans and discovered about a year later that it was not compatible with a particular plastic bushing. This adversely affected the shifting and it cost me $1100 to replace the ruined parts.
dude i just noticed u always have no problems with ur GT. Are u a lucky b.a.s.t.a.r.d or what? lol
No way Horn,
I had the popping front struts at 700 miles and TSB done at 2500. It took a long time to get the parts in. I also had the drivers door handle replaced due to the bad spring inside. The shop that did my gears tried to pull a fast one on the first install. The gears whined something awful and replaced w/ the proper Ford 4.10's. I watched them open the box this time.
I picked up the Redline brand full synthetic for both the rear end fluid, and also the oil for the tranny(manual). I just have not had a chance to get it done. I am wondering if I should pick up the friction modifier just to be on the safe side, and if I should have my dealership do the job, just to cover my butt.
Re: TSB06-19-2. As mentioned above I recently had this work performed at the dealer at 4748 miles. My car now has 5619 miles and the noise is back. I hope this doesn't become a monthly ritual.
Gear Whine w/ Royal Purple 
