Is Royal Purple ATF worth it?

[Oro_O]

With a little bit of a drive, I can get a few gallons of Royal Purple Max ATF for a steep discount. Is it worth the effort?

I don't have any transmission acting up (or it would be fixed!), so I'm not trying to use it as a band-aid for a problem. All the cars have fluid in good shape and drained/filled every 25 to 30k miles. So I would just use it in rotation to drain/fill in place of the otherwise DexIII, TIV, etc. Is this stuff really superior and better than normal good fluid like Valvoline DexIII or Mobil T-IV?

 

[buster]

I honestly doubt it. RP is nothing special IMO.

 

[nascarnation]

Think how much better you'll feel going down the road with that RP sticker on your back window. It even defies the laws of physics vs other ATFs...."Max ATF significantly reduces heat to extend the life of your transmission."

 

[sloinker]

Probably OK if cheap enough.

 

[TheBig2003]

If it is cheaper than Valvoline Maxlife ATF, Castrol Transmax Full Synthetic ATF and Super Tech Full Synthetic LV ATF, then sure. Otherwise, any of those other three full synthetic transmission fluids will be just as good.

 

[Oro_O]

Yeah, I don't quite see how it could be vastly superior to other Full Syn Dex/TIV compatible fluids.

It was $30 for 10qts so to cheap to pass up, I got it.

My truck/suv has an accessory cooler out front and a very sensitive temp gauge I mounted on the A-pillar. From use I know what the atf temp should be from just knowing my speed and the outside temperature. So when I swap some of this in, I can tell within 10 miles if it really does reduce temps vs. regular DexIII. It has a clean fill of 9/10 qts. of Chevron MD3 with 25k miles on it (I rebuilt it 25k miles ago); I'll swap the pan volume (drain/fill) and see what happens.

 

[RazorsEdge]

Yeah, I don't quite see how it could be vastly superior to other Full Syn Dex/TIV compatible fluids.

It was $30 for 10qts so to cheap to pass up, I got it.

My truck/suv has an accessory cooler out front and a very sensitive temp gauge I mounted on the A-pillar. From use I know what the atf temp should be from just knowing my speed and the outside temperature. So when I swap some of this in, I can tell within 10 miles if it really does reduce temps vs. regular DexIII. It has a clean fill of 9/10 qts. of Chevron MD3 with 25k miles on it (I rebuilt it 25k miles ago); I'll swap the pan volume (drain/fill) and see what happens.

Let us know if you see a decrease in temperature

 

[TheLawnRanger]

Not to me. However, if the price is right and you want it, it's worth it. That's all that matters.

 

[bbhero]

Yeah, I don't quite see how it could be vastly superior to other Full Syn Dex/TIV compatible fluids.

It was $30 for 10qts so to cheap to pass up, I got it.

My truck/suv has an accessory cooler out front and a very sensitive temp gauge I mounted on the A-pillar. From use I know what the atf temp should be from just knowing my speed and the outside temperature. So when I swap some of this in, I can tell within 10 miles if it really does reduce temps vs. regular DexIII. It has a clean fill of 9/10 qts. of Chevron MD3 with 25k miles on it (I rebuilt it 25k miles ago); I'll swap the pan volume (drain/fill) and see what happens.

At $3 a quart... That is a fairly good deal there. You did fine to get that RP.

Pennzoil full synthetic ATF that is Dexron VI licenced and Mercon LV is $4.68 a quart. And that is considered a pretty good deal on here by most people.

 

[Oro_O]

Let us know if you see a decrease in temperature

Yes, I'll definitely report back.

I may go ahead and swap it in this weekend; I know I am planning on towing a trailer with it one day next week. That will definitely let me see if it makes a difference vs. standard dino DexIII in it. And as I mentioned, it's a recent 100% "clean" fill of DexIII so it's a decent apples-to-apples comparison.

 

[RazorsEdge]

Yes, I'll definitely report back.

I may go ahead and swap it in this weekend; I know I am planning on towing a trailer with it one day next week. That will definitely let me see if it makes a difference vs. standard dino DexIII in it. And as I mentioned, it's a recent 100% "clean" fill of DexIII so it's a decent apples-to-apples comparison.

Anything new to report?

 

[Oro_O]

I had some other projects last week and didn't get to it yet. Yesterday was going to be the day and we had rain harder than I've seen in years. I'll likely get to it tomorrow. I'm curious, too. I also want to lift the truck to do two other small maintenance items so I'm eager to do it.

 

[Oro_O]

OK - didn't test the temp yet, but I did a baseline drive today to take exact readings for "before." The weather is identical tomorrow so I'll do the drain/fill tonight or tomorrow a.m. and repeat the exact drive in the same ambient temperature/humidity. I'll lay out the test parameters now:

Test Mule: My 1998 Acura SLX, which is a slightly gussied-up last-generation Isuzu Trooper. Great truck. Pics below.

Transmission: GM 4L30E. I rebuilt it about five years/25k miles ago. It had then a fresh fill of Chevron MD3 (Dexron IIIH). No additives. At this time, my plan WAS to drain fill it and add Mobil 1 synthetic + 10oz bottle of Lubegard Red. I will not add the Lubegard as it would likely drop the temps on its own. I will drain the pan and add only the Royal Purple ATF.

Current Transmission temps: After the rebuild, I installed a slightly over-sized tube/fin ATF cooler in front of the radiator, downstream of the internal radiator cooler/exchanger. I have a GloShift trans temp gauge on the A-pillar so I am familiar with the trans temps in various operating conditions. The temp sender is threaded into the transmission test port on the bellhousing base, adjacent to the pump. Thus, the temps are an accurate reading of the pan temps before the fluid is circulated through the transmission. These are typical temps:

Steady 65mph on the highway = ambient temp + 75/80F (depends on absolute ambient and humidity).
Sitting in traffic = ambient + 95F/100F

Today was middling humid and 60F at noon. It was a steady 140F on the highway. After exiting the highway and going through traffic home, some hills, it was 160F. We'll see tomorrow as I do the same drive after the Royal Purple is in. If it has a lot, or even a reasonable fraction, of ester synthetic in it, it should drop those temps.

Test mule. My bomb/nav is in the pilot's seat. She went along on the test drive today and will tomorrow. She will provide independent verification of my observations. :

Transmission (well part of it - thoroughly rebuilt):

Instrumentation:

Clean, new RP Max ATF:

 

[Oro_O]

OK, results in. I got motivated and did the drain/fill this afternoon. Total swap volume about a gallon, maybe a bit more. So the transmission is roughly 55% Dex III with 25k miles on it, 45% fresh RP ATF.

No drop in temps, but it was noticeably smoother.

It was about 3 to 5 degrees warmer than before, and the transmission was always about 4 degrees (or so) above what it was at the earlier drive. The truck has a very accurate thermometer in the overhead console so I can monitor the ambient temperature really closely. Since I have such a large auxiliary cooler installed, it might be driving the cooling factor more than a factory set up. Perhaps it would drop temps in a "factory" unit or one without a cooler of any kind installed.

The transmission shifted very nicely before; now the shifts are almost unnoticeable. It was a pretty stark difference. I did not expect this.

Because these transmissions are really a little over-stressed in this application, I will for sure be using a full synthetic DexIII compatible (meaning full viscosity) fluid going forward. As I mentioned above, I planned on putting some Mobil 1 ATF in it. I can't say if the RP is better than the M1, but my initial "seat of the pants" impression is positive. Which I would point out is NOT what I expected. I expected to see no difference. So my bias was the other direction and I don't think it's a "placebo effect."

My observers was, by the way, thoroughly unhelpful. Mostly she just sat there and did her nails:

At one point I said "McNuggets" and that got her attention.

 

[RazorsEdge]

OK, results in. I got motivated and did the drain/fill this afternoon. Total swap volume about a gallon, maybe a bit more. So the transmission is roughly 55% Dex III with 25k miles on it, 45% fresh RP ATF.

No drop in temps, but it was noticeably smoother.

It was about 3 to 5 degrees warmer than before, and the transmission was always about 4 degrees (or so) above what it was at the earlier drive. The truck has a very accurate thermometer in the overhead console so I can monitor the ambient temperature really closely. Since I have such a large auxiliary cooler installed, it might be driving the cooling factor more than a factory set up. Perhaps it would drop temps in a "factory" unit or one without a cooler of any kind installed.

The transmission shifted very nicely before; now the shifts are almost unnoticeable. It was a pretty stark difference. I did not expect this.

Because these transmissions are really a little over-stressed in this application, I will for sure be using a full synthetic DexIII compatible (meaning full viscosity) fluid going forward. As I mentioned above, I planned on putting some Mobil 1 ATF in it. I can't say if the RP is better than the M1, but my initial "seat of the pants" impression is positive. Which I would point out is NOT what I expected. I expected to see no difference. So my bias was the other direction and I don't think it's a "placebo effect."

My observers was, by the way, thoroughly unhelpful. Mostly she just sat there and did her nails:

View attachment 59915

At one point I said "McNuggets" and that got her attention.
View attachment 59916

Lol ! cute dog

Glad to see your efforts paid off

 

[Oro_O]

Lol ! cute dog

Glad to see your efforts paid off

Thanks, she's a gem.

Despite it NOT doing what we tested it for, at least in my vehicle, I am pretty impressed with this stuff. I was so focused on paying attention to the trans temps, ambient temp, watching traffic, I forgot to pay attention to the overall driving dynamics. About 3/4 of the way through, I was like, "Wait, where's the shifts happening?" They were so smooth I was not noticing. The car, which is in VERY good tune/condition despite the higher mileage and age, was just SMOOTH. I drove the last mile or two back home consciously monitoring the shifts, and they were nearly invisible. The 4L30E is an "adequate" GM transmission for lightweight vehicles, and no one has ever given it higher praise than that. This thing felt Jaguar smooth. Egads.

I'm impressed even if it didn't do what we discussed above and we were looking for. As I said above, this change was supposed to be a gallon of Mobil 1 ATF; that will be my "floor" atf going forward in all vehicles. I have a lexus due for an atf drain/fill in 5k miles (might be a year given current driving habits), I think maybe next week I'll put the remaining gallon of this in it and see what it does.

I have to drive to Tacoma tomorrow morning for a motorcycle-related nonsensical errand. Instead of a bike, Volvo or Lexus I'll drive this and give it a more thorough test.

 

[meep]

Someone gave me a bottle of an RP concentrated oil additive back in the late 90s. I’d never heard of the stuff, but added a little bit of it to the PS reservoir in my 97 legacy. It made a wonderful difference in removing the stiction from the rack; I quite enjoyed it in that application.

 

[Tikka]

Hi.
The Isuzu was a great vehicle. Very popular in UK. Is it Diesel or Petrol?

 

[repairman54]

I remember buying RP at a discount store in 1972 and on the label it said ''refined from previously used motor oil''.
But it was purple and cheap and worked fine in my '60's cars that leaked and burned oil.
Not worth the price for me anymore...

 

[MolaKule]

Love the navigator. Maybe she can give us an overall "RPaw-review?"