View Full Version : Syntorq oil for NV4500

02-17-2006, 02:33 AM
I have a question that relates to the eqvilancy of Castrol Syntorq oil and Castrol TAF-X. The reason being I recently swapped a 6.5 and a New Venture 4500 into my suburban, but most importantly! that I live outside the US, therefore I cant go to any parts store here in Denmark and buy the Syntorq oil they recommend. But research have led to US sites, where Lotus Esprit owners have used Castrol TAF-X 75W-90 which is only made in the UK, they were told from Castrol USA that this lube is the same as the Syntorq! are there anybody who knows this for a fact or can point me in a diriction to somebody who knows, before i ruin a perfectly good transmission.

02-17-2006, 03:06 AM
Well, It all depends on who you talk to and believe.

The story I heard was Castrol Syntorq was specially formulated to help cold shifts in the NV4500 and its better formulated for the synchros of the transmission. And an agreement was made between (GM, NVG, DiamlerChrysler?)and Castrol for Castrol not to sell/market it retail in 1 qt containers. ????? about that story it just may be an economics thing for Castrol because of market demand. Castrol does sell it wholesale in larger containers. A few transmission shops repackage it for sale to individuals check out

quad4x4.com and Standardtransmission.com

You can also get it at the GM dealership or a Diamler-Chrysler (where I bought mine cheaper than GM).

Amsoil has something they claim is equivalent but its nearly as expensive as GM dealership. Redline also recommends mixing (2) of thier synthetic gear oils for a replacement. I have read posts from others they work fine.

I have had some experience buying Castrol lubricants for industry and European vs US trade names and formulations are sometimes different due to ingredients and environmental laws.

Sorry for the long post and not specifically answering your question but I am not sure anyone can. I am just trying to explain we (in the US) also have the same type of problem figuring out exactly what is Syntorq. You will probably be alright if it is a high quality synthetic gear oil of the correct viscosity compatible with the syncrhos (read quad4x4.com). And If the transmission does not shift smooth cold I would definately change it.

Post back what else you find.

02-17-2006, 09:12 PM
Hi John,
I asked the same questions when I put a NV4500 in my jeep and couldn't find answers.
Few days of research and a conversation with the product manager for the NV4500 at new venture got me closer. Syntorq was formulated to address the high heat the NV4500 created. It is sold under GM and Chrysler spec numbers 9985648 and MS-9224 respecively.

The new factory fill for spec MS-9224 is Penzoil Syncromesh. http://www.pennzoil.com/products/gear_oil/syncro_fluid.html

Bought 3 cases from my local dealer for the price of a gallon of Syntorq.


02-18-2006, 05:26 AM

Recheck info. Are you sure you have a 4500 and not a 3500?

I rechecked my info. I looked at qaud4x4.com again and my helm manual again.

According to 1997 GM shop manual (helm)

NV4500 says use Castrol Syntorq LT (4) quarts
NV3500 use Synchromech P/N 12345349 (11) quarts (verbatim I think the "c" was a typo in the manual and it means synchromesh) The link to penzoil site matches that part no.

Quad4x4.com lists Castrol syntorq as either
GM- 12346190 or Mopar 4874459 (MS-9070)

I have an extra quart of the mopar oil right here and on back:
04874459 SAE 75W-85 MS-9070.
"This unique synthetic transmission fluid is formulated for the NV4500 5 speed wide ratio transmission. Maintains proper shift qualitiy in cold temperatures. Do not use in other manual transmissions unless specified in the DiamlerChrysler service manual. GL-4, MIL-L-2105 rated."

I bought this summer 2005. And have put ~ 10,000 miles on new clutch and fluid change in my NV4500 with no problems.

I thought www.standardtransmission (http://www.standardtransmission) also sold Castrol Syntorq but don't see it on the website now.

02-20-2006, 06:49 PM
Can you get Redline or Amsoil over there? I have used both in my NV4500. Currently running 2qts of Redline MTL and 2qts of Redline MT90 as Redline recommended. No issues. Thought the shifting was a bit "notchy" with the Amsoil but run it for 50K without problems. The Redline seems a bit slicker. My synchro's are a bit toasted and the trans will grind a bit between 1 and 2 if shifted too fast but it has been that way since I have owned it for 110K. RT

03-05-2006, 02:40 PM
thanks all for the replys I have now, with a lot of help! gotten the oil I need, I still havent found out just what the difference is with the oil we have here in Europe and what you guys have in the States. The closest I have gotten to an answer is very much like what Hubert wrote! the Syntorq is transmission specific and that is due mainly to the fiber inserts in the Syncros they need a special lubricant additive found only in the syntorq, and the people I spoke to here in europe, couldnt tell me if other oil's had it or not, therefore I had it shipped through an American parts specialist for around 250 danish kroners per quart! that you can divide with 6,20, which gives $40 per quart and you all know how much is needed, I may start importing this myself. but now I at least can rest assured that I wont ruin my NV4500, just because I wanted to be safe not sorry.

07-02-2008, 06:20 AM
Castrol does sell it wholesale in larger containers. A few transmission shops repackage it for sale to individuals check out

quad4x4.com and Standardtransmission.com

Any idea how to get the wholesale containers? Quad4x4 stopped selling it for awhile - they do have it back now, but I was thinking whether it would be worth just getting a container. Searching the Castrol site I wasn't even able to find Syntorq.

And what is a "larger" container? Five gallons? Thirty gallons? Fifty-five?

07-02-2008, 08:52 AM
Its been a while since I did the research but at the time read a Castrol Distributer can sell a "drum". I would assume you would have to order it. Its fuzzy what "drum" sizes were availiable 55 gallon and maybe a 35 gallon???? I wasn't interested in such a large quantity so never actually persued it.

3-4 years ago I think local dealers GM was about $22-26 per quart and Dodge was $16-19 for reference.

07-02-2008, 12:29 PM
Quad4x4 has it for $35 for a two quart container - so about what Dodge is charging. They had me a bit scared when they stopped selling it, but I guess going to Dodge would be just as easy as going to Quad4x4 for it.

I'd probably get a 5-gallon pail of it if it were available, but even 30~35 gallons would be more than several lifetimes worth for my use...

07-04-2008, 12:16 AM
The consensus that I got over at tdr1.com for my nv4500 behind my Cummins in my Dodge was Royal Purple MaxGear 75w-90 with a GL-4 rating. I have used that for the last few years. I have 178,000 on the original trans in my Dodge. Just keep in mind that the 5th gear nut has been known to sheer off in the Dodges, I don't know about in the GMs.