A less confusing Royal Purple Thread
 

Okay so I have been reading through posts all day. I have just changed to 410's and I am going to put Royal Purple Max-Gear in there. There seems to be some confusion and I am hoping to get it straitend out with this post. I plan to use RP 75W90 + Friction Additive. I see that may people use 75w140. What am I suppose to use in the car (96 Cobra). Also I see that some people dont use the additive because RP says it comes with it. But others say they have had problems and then had to add it later. Can I get some true stories on this from some of you folks? Is there anyone out there running 75W90 + the additive that has had problems, and what kind?

Thanks.[/align]

RE: A less confusing Royal Purple Thread
 

if using the bottle of friction moddifier makes you feel better do it. its like 4.00 a bottle at 50resto it wont hurt anything. im using rp 75w90in mine.

RE: A less confusing Royal Purple Thread
 

Ford changed to the 75W-140 sometime in 2002 I *think* and from what I have been told it had something to do with their SUV/Trucks and the clutch packs having problems under heavy load.

All unsubstantiated so if anyone has a source direct from Ford fire away and let's put this one to bed!

As for the additive, I would add the bottle anyway even though RP has it inthe bottle.
In fact the Mobil 1 Synthetic Gear oil, which has the modifier included in it, says something to the effect that for *severe operation* additional friction modifier should be added.
It won't hurt anything to add another bottle.

A few things to warn you about.

1. Check the fill plug BEFORE you remove the differential cover. IOW make certain you can unscrew it and it is not stripped or frozen in there.

2. Wear gloves and throw away clothes because nothing stinks worse than this oil and once it touches your clothes, or you for that matter, it will stink badly.

Good luck!

RE: A less confusing Royal Purple Thread
 

I didnt do it myself, I had it done, its already back together.

RE: A less confusing Royal Purple Thread
 

ya i run the R.P. 75-90 as well i have not ran into any problems.