Royal Purple For Tr-3650

I own a 2003 Mustang GT equipt with the Tr-3650 transmission. I recently purchased a new clutch(Exedy Mach 400) and TOB(ford racing), I took it to a shop and had my guy use Royal Purple synchromax. And honestly after installing it was nearly impossible NOT to grind going into second. I assumed that it was just the new clutch at first, But after some time I could tell my clutch operation was fine and now I was thinking, maybe they didn't put Royal Purple in? So I drained my transmission fluid completely, and believe it or not... That S**t was Royal purple. Because it was PURPLE. Well I didn't buy Royal purple this time to refill. I bought Valvoline max life ATF. Filled it up through the shifter (3.2 quarts), And looked to see if the grinding stopped. Yes. It did. The grinding was because the Royal Purple! While using Royal Purple, my transmission would get so hot that my windows would fog up, loud synchros, grinding, and trouble getting into gear. I mean that Royal purple was only in there for 500 miles and it was seriously tearing up. I just thought I'd put my honest thoughts on the transmission fluid for the Tr-3650. And an honest opinion about putting Royal Purple Synchromax in your Mustang.

Benzboy85 said:

That's crazy. Have you tried their oil? I'm having allot of drive train noise after I put it in there.. might need to switch

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Yeah you might need to.

Moosee1955 said:

Full synthetic oils don't play well with non syn's. If you had too much regular ATF in your trans, didn't drain all out, could be your problem. Regular petroleum oils, have to be thoroughly flushed out, when switched to full synthetics. Especially true switching from dot 3-4 brake fluid to silicone dot 5. They just don't mix. Don't know if for sure if that was 100 percent your problem, but that's my best guess. Synthetic/ non synthetic mix like oil/ water. Not well. Well that's my 2 cents from smarter people than me.


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Yeah I agree with a lot of that. Both the RP and the Valvoline max life are synthetic just totally different fluids. An ATF is recommended by the factory but soooo many people online say Royal purple is the best so I just had to try. Turns out you should just stick with the ATF unless you want to destroy your transmission!

Moosee1955 said:

I run Mobil 1 5w30 in my 2000 5.4 expy. Been very happy, even runs a tad smoother. But in my trans, I use Ford dealer mercon v. It shifts so smooth, I don't mess with it. I just change every 25-30k. My trans is too expensive to mess up trying different fluids. Glad your shifting a back. I've had three fox body stangs, I've always used the ATF from dealer made for T5 transmission.


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Yeah it was only in the transmission for 500 miles so it could have been way worse. Truly is an expensive mistake that I could have made. I should also be reciving my shifter in the mail today or tomorrow and I'm curious to see if that improves drivability.

PDOGG74 said:

Hello I too have ROYAL PURPLE in my tranny as well. So far the shifts are smooth and the tranny only gets warm if I am sitting in traffic and its near 100 degrees. Even if I am putting a load on it, it does not get warm or hot. When I bought the car it had royal purple in it and when I changed out my clutch I put royal purple back in it since a little spilled out. Maybe it is hit or miss with the fluid or tranny.

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Yeah dude I totally think it's hit or miss. Some people swear on it, and say it works quite well. But some people like me have not had good experiences