Sorry to dredge this up guys, as I'm sure a lot of you since the GTO first came back have heard or debated some sort of issue with this "mythical" fluid. It was time to change the gear oil this past weekend to get ready for track time and Ive had some limited slip noise on left turns and the infamous clunk from incorrect or old oil in these damn rears on the GTOs. I know by now your thinking this should go in the GTO section but maybe in this section I can get some more insight in the primary reason I CANT FIND THE DAMN FRICTION MODIFIER!!! Sturaco 7098 is what is supposed to be added to the 75-140 in these rears. GM has changed the number from the owners manual into a QUART bottle of 75-90 NOT the one oz additive. Now to the questions, since Ive learned 7098 isn't a PN, but more of a certain blend could someone shed some light on the differences between the blends? Question two, can some parts whiz kid tell me why GMs dumb *** changed an additive to a one quart bottle of the INCORRECT weight? Question three and I believe the last question, can some sort of "specialist" or sponsor or expert or anyone that's wondered these same things I am wondering tell me what is the best, CORRECT damn fluid and additive to use in my car? I'm sorry guys if I seem a bit upset but I'm a stickler for the correct parts no matter if its my vehicle, or a customers I'm working on, and especially when I have a jack *** parts guy at the local GM dealer trying to shove a quart or the wrong **** in my face telling me "It's right, because that's what the computer says!". Thanks for listening, I'm sure you can relate to my frustration in some way.

 

Hello GoatPilot87:

Apologies - first time user to this site, but I did see your question on the Sturaco 7098 friction modifier product and thought I might be able to answer some questions. The Sturaco 7098 friction modifier is currently manufactured by Houghton International (www.houghtonintl.com) and since the 1960s has been an effective solution in solving engineering issues with chatter and NVH on various applications (including limited-slip axle differential applications). Although not provided directly to the automotive factory service centers in most cases, Sturaco 7098 is provided directly to both major automotive OEMs as well as major oil companies where it is applied to the axle gear lubricants (usually an effective range of between 2%-5% by weight for Limited-Slip applications). In many cases, 4 oz bottles can be purchased that often list the Sturaco 7098 additive on the label (i.e. Ford Motorcraft Additive, Ford Racing FM etc). I can't really speak to the GM question and/or the reasons for the change in weight, but I did want to let you know that the Sturaco 7098 is not a "mythical" fluid and I guess that would make me that Sturaco SOB. Hope this is at least is an initial help.

 

Wow, you named your ID after my thread. Hmm...weird? Sorry I havent been following my own thread.Weve been dodging tornadoes here in Alabama. I live in Hazel Green, a few miles from Harvest where a EF4 touched down. Seven dead in my county alone and 230 statewide. Pray for us guys, its been a rough week, just fortunate I still have a roof over my head.

 

As for YOU being the SOB, no. Just the parts guy I dealt with. I understand they "mix" the modifier in most diff oils now, Ive just read up a LOT about different people having my same issue and the 2-6% rule wasnt enough. I just threw what I had handy in there for now which is Valvoline Syn something 75-140 synthetic and 4oz of some Chrysler additive I had in my toolbox. So far so good the clunk and **** went away.

 

Glad to hear everything worked out well and thoughts and prayers to those effected by the storms for sure.

Yes, the Chrysler additive would have been the Sturaco 7199 product (Chrysler MS 5630 approved) and is another good friction modifier for performance....