I purchased my car about a month ago (64k miles) and had the transmission fluid replaced with Royal purple about two weeks ago. I thought it would help smooth out the transmission a bit more (it wasn't that bad to begin with honestly). I read on this forum while searching that no one had really done Royal Purple and someone actually emailed RP directly to ask what to put in the MB gearbox - their reply was that they didn't have anything that would really work and to stick with MB fluid. They were right.

I put 75w90 RP in it and when the gearbox is up to temp it's buttery smooth and wonderful. My problem is that when cold the 1-2 shift has a pronounced clunk and crunch on a consistent basis. I can't stand it and it can't be good (so i've been starting off in 2nd for now until the oil gets up to temp).

OEM fluid goes back in on Wednesday. Just thought I would share this for future searches and indexing on this forum to definitively say RP is great for a lot of applications but there is a reason they didn't recommend usage in this car - it doesn't work.

Redline might be better as it's synthetic but frankly all the fluid swapping is adding up and i'm going to go back to fresh OEM fluid (which can't hurt the shifting performance) and call it a day. If nothing else I basically performed a tranny flush on the car.

Just wanted to share the results!

 

It's not clearing from the synchro assembly when cold.

Stick to approved products.

 

you used 75w90... should've went with the Synchromax formula... this is a synthetic that many praise on the e46 bmw forum... as well as the renntech forums for 6-spd porsche cayennes.

 

sometimes a really slippery synthetic oil does not work well in gearboxes as the synchros actually work as a brake on the gear to slow it down so that you can engage (think of a reverse type of drum brake. When you have a very slippery fluid it does not slow the gear enough and hence the clashing or clunk when moving from one gear to the next. Usually snychros are a bronze type of part and over time they do wear out from all the 'braking' the gear speed. The slippery synthetic fluid can have a similar effect.
If anyone rebuilt a gearbox you would know what I am talking about, done about 3 in my life but old British sportscars, the principal is the same though. I had a problem with my TR6 using a molyslip type fluid/additive after rebuilding and shifted poorly, a simple change to standard gear old solved the problem


I think the real lesson here is stick to approved fluids, the engineers have already done the legwork might as well as use their wealth of knowledge gained through hundreds of thousands of miles testing


.

 

Royal Purple does not have a single approval. Do not use their products. They have no technology of their own. They just buy it in from the additive pedlars. They have no reasearch labs etc.

 

Blam!

 

I used to use redline mt-90 on my mazdaspeed 3 and that fluid was the best gearbox fluid I have ever used. Granted this wasn't on a MB though

 

Are you talking about the transmission fluid or differential oil? Because some have used the Max gear oil for their differential and haven't had problems and some used redline gear oil as well.

 

Hmm... some insight into all these accusations would be nice.

 

why take chances on non approved fluids? Your car is the second most expensive investment. Are we using obscure stuff just trying to be different and go against the grain; save tons of money or think that this snake oil will give us an extra 10hp??

Each specification is engineered for your car, eg in the case of my TR6 if I use a gear oil that is API GL5 fluid instead of API GL4 it corrodes the hat bushings in gearbox and causes failure of these components.

 

Search the entire Benz product approvals listing & you will find that Royal Purple do not hold a single Benz approval for any application.

Royal Purple's annual turnover would not pay a fraction of the salaries at a major oil company's research facilities.

 

I don't disagree with you, but I don't completely agree with you. As far as you always going by specifications and playing by the rules, this is a good thing and of course you are properly following what your book says. It seems that this is always the case with you. Now stating that Royal Purple is "obscure stuff" is a little different. QC laboratories is a private R&D Co. that gets hired by other companies such as Royal Purple to do their oil analysis tests, and work on improvements that can be made. This is a sort of outsourcing of research if you will. I was an employee for QC labs in south hampton, PA and actually worked with royal purple analysis, so to say that RP does not perform research, you would be wrong. Though I did not measure anything with transmission oil ( samples of 10w-30 motor oil only), I can tell you that metal deposits in Royal Purple oil samples were relatively low compared to penzoil, amsoil, and mobil 1 . I have also read numerous posts on other BMW and Porsche forums praising synchromax for help with "cold shifts". As far as you bashing Royal Purple... it seems that you are being a little bias... you are basically the type of guy that does not like "mods" or anything that is not OEM. You like to play by the books... and that's Ok, but the annual turnover of a company and whether or not it pays salaries has nothing to do with the quality of that companies products. Royal purple is relatively new, so of course they have a small payroll, but they have worked hard to compete and it is showing. I have done the research myself, I have used Royal Purple 5w-30 motor oil in my old 350z, and use synchromax now in my wife's cayenne 6mt trans. IMO it performs great, but lasts a lot less that your conventional "MB approved oils". Meaning the oil has to be changed more frequently. Maybe you should follow the books, maybe you should try out synchromax... I don't know that is up to you, but telling people that this company is working with "additive pedlars" is getting extreme. You are also stating that RP is not under the list of approved MB oils. This is because MB never tested any RP oils in their vehicles, and if you have proof that they did, I would be interested in seeing the oil analysis results for that. The thing that get's me is that I read about the people that complain that RP is not "approved" or not a good oil, but not 1 post from these guys has any factual information on why exactly it's not approved. Maybe a reason from MB USA would suffice ? Maybe you, Mr. Ruck, would like to call and find out?

 

I've searched.... it's just an approval list, where is all the good stuff?... I don't see anything about Royal purple's synchromax product?

 

@vdemon311

Before you vent your personal attacks perhaps you should properly quote the source who said additive pedlars and quote them and their 'mods' preferences

Not sure who you are bashing, me or Glyn or both I never said anything bad about the product all I said that it was obscure and not approved by MB, and that I sometimes question why some seem to want to venture off the approved fluids list thinking that it is the new wonder stuff. But since it is not one of the MB approved specs it is a chance that I don't want to gamble with. However the last thing I want is sludging in my engine and some oils do it more than other in some manufacturers engines (Audi A4 1.8T and 2.0T comes to mind). Some mods I think can be better than OEM because sometimes the bean counters have their hand in the selection process a bit too deep.

I am sure that if RP was the recommended oil and Mobil 1 was not, everyone on the forum would be singing the praises of M1. And when I said obscure, I mean that it is not a common item that is easily found, akin to trying to buy Agip or Elf oil here in North America. Until RP has an MBxxx.xx number on the bottle I will stick to approved formula's

 

Not bashing anyone.... you and glyn are both valued members... I have read lots of great info from the both of you. You asked me a ?... I gave you an answer. Why would you put anything in your car that isn't approved? I guess its just personal preference/experience on past vehicles .. Regardless, no harm intended

 

I've stated it before & I will state it again. Benz & the oil industry spend a fortune developing & approving products for Benz vehicles. This is for the benefit of owners to ensure long trouble free life.

If little companies like RP etc want to be taken seriously the they must submit samples to Benz, pay their test fees & get their products approved if they will in fact pass the testing regime.

I come from the industry. I am completely au fait with the Benz testing regime. I will not recommend non approved products on this forum. It would be irresponsible to do so & damage someone's vehicle.

Oil is not just oil. Benz use yellow metals in specific GB components which are subject to attack by certain sulphur containing additives. Why do you think so few products are approved for this application? Because most fail to meet requirements.

 

+1

Exactly what I was saying about certain components in my TR6 gearbox and how API GL5 gear oil will ruin these yellow metal bushings, they specify GL4 non hypoid gear oil

Why take a chance? It is not like the approved MB fluids are $1000/L or the non approved oils give you an extra 10hp. Are people trying to be different for the sake of being different? You have to think there is a reason why car companies spend billions of dollars on developing a car and test it for hundreds of thousands of miles or millions and do a tear down to see what is taking place

 

yeah, i agree, you shoukd stick to oem and mb approved oils..

 

Stick with what your happy with. I went from MB to royal purple synchromax to redline MTL. So far I am happiest with redline MTL and that is what I am sticking with for this car.

 

That's fine - You may do as you wish with your own car. When the first to second synchro pack fails or your bushings look like Gorgonzola cheese - don't come crying. Lubricants are a design component of the vehicle today.

 

How long (miles and years) have you been using Redline MTL?

 

Reading through this all sounds like the OP put gear oil instead transmission fluid in his flush. RP synchromax and redline mtl are transmission lubricants. RP Max gear 75w90 is different/gear oil. Sounds like wrong fluid/oil used in tranny flush.

 

no more than 4 months, 7000 miles

 

Redline ATF-D is MB approved for certain auto applications, MTL is on it's way as well...

 

Glyn, the getrag transmission prefers thicker lubricants, so why wouldn't MTL help with synchros, especially in high mileage cars? MTL is a thicker lubricant than your standard MB ... My 1st to 2nd shifts improved so much after changing to MTL it is like night and day. With many things that are not approved, there is always an exception.