ILLCOMM

There are undoubtedly some vested interests here, so I am curious how this thread will unfold. Complicating the matter, I have only second hand knowledge, so I cannot be authoritative. Just looking to kick off a discussion...

That said, I am hearing that Delvac transmission fluid has been a commonality across numerous transmission rebuilds in our GT cars. When internals are directly compared to transmissions running something else (notably something like amsoil synchromesh) the difference is obvious. Costs of these repairs can easily reach $10k.

Specifically, the assertion is that Porsche race cars use delvac, so why shouldn't the street cars, especially those on the track. I think this logic is probably the reason many of our cars have Delvac. Seems sound, but...

The argument against this logic is that these race cars (all of them, mid 2000s and beyond) don't run synchros (they are dog engagement and sequential) and as such their fluid doesn't need to be mesh compatible.

Delvac, or so I hear, is not a synchro mesh trans fluid, it's more of a high pressure gear lube (maybe more appropriately suited for semis). Hence the resultant issues.

There are people FAR more knowledgeable about this stuff here (Matt from GT Gears is one that comes to mind), so I am simply asking whether there could be any truth to this?

Spyerx

WHO are you hearing this from?

Brian Copans? Bill Rader? Matt?

ALL of these transmissions are expensive to rebuild and ALL of them will require maintenance when tracked hard.

More important is changing fluid often, I do mine when I do my oil, every 6 track days.

GTgears

Hello,

I keep this thread bookmarked because this was kind of laid to rest half a decade ago.
https://rennlist.com/forums/993-foru...for-993-a.html

Read Bill Verburg's comments carefully, especially the stuff on page 2. You have a flawed premise. Delvac, while rated as a GL5 oil, is NOT intended soley for cars without synchronizers. As Bill points out, SHC/Delvac was the originally supplied and only recommended fluid on all 1998-2005 RS/RSR/Cup cars with synchros.

Post pictures. Show me these directly compared internals with Delvac versus Amsoil. It will still be purely anecdotal, but if you've got something "measureable" to bring to the table, show it.

Keep in mind, I don't have any horse in a gear oil race. If you search around you'll see that I've consistently told guys that Lubrication Engineers makes a better oil than Delvac. There are better oils out there. It becomes a cost benefit question and the question of whether spending $500 less on gear oil per year is going to cost you anything extra when your rebuild service interval comes up. Please be sure to post miles, track hours, frequency of oil changes, and any other relevant details you might have regarding your examples when you post pictures of these obvious differences that you attribute to a different gear oil selection...

GTgears

ps. I don't mean that post to sound as an indictment. I suspect whomever is telling you this wants to sell you Amsoil because that's where he makes good money. I'm calling BS on his story. If his story is legitimate he's got more than sitting across the desk discussing your bill for a gear oil change to back up his claims.

When Paul Guard started telling people that LE oils would drop your gearbox temps 20-30 degrees F, it was based on back to back sessions with the same car with the two oils in it using a pro team to test and verify. He didn't just pull that out of his ****. He verified it based on the claims of LE's salesman. Always be wary of a saleman. Trust but verify? Or just verify.

ILLCOMM

Matt, many thanks for the reply.

Clearly, if the fact about Delvac in synchro race cars is true then part of what I heard is bunk.

I will see if I can't get some of what you request, but it will have to come from someone other than me. (I am just a consumer of these machines and have no serious technical ability.) That said, the folks I heard this from are not amsoil salesmen and I can't for the life of me imagine why they'd care about the brand of oil/fluid beside its performance. They just see the internals and this was an observation they have made.

GTgears

Who is it?

ILLCOMM

I had a conversation with a guy who takes these transmissions apart and puts them back together. This was just his observation. I'll let him decide whether to participate. Not my place to call him out as it was a private conversation.

GTgears

So be it. Just trying to establish whether or not we are even dealing with someone who knows how to properly analyze wear.

Your opening post says there are vested interests. I have no vested interest in what oil anyone uses. I do have a vested interest in my parts lasting and a poor oil or poor care would reduce their lifespan, hurting my brand reputation.

That said, in my experience, getting anything actually empirical from car owners is like herding cats. I'll be interested to see if any real data gets presented or if it's just like all the engine oil threads where guys argue about their favorite with very little basis in technical truth.

The best are the 915 gear oil debates. These guys argue back and forth about Kendall and Swepco. All these single instance testimonials of how a guy bought a car, changed the gear oil to one or the other and magically it shifted better. Of course it shifted better. They just took out old oil and put in new oil!!!

ILLCOMM

Matt the "vested" comment was in no way directed at you! Apologies if it seemed that way. I mentioned you by name solely because you're such a respected person in this arena. (I am a very happy customer of yours!)

The comment was because I know some shops that recommend/use Delvac, that is all I was alluding to. I am sure they recommend it in good faith, and likely would be vested in defending such a recommendation. As you point out that defense may be entirely right. I am open minded. Just curious, mostly because my "guy" has taken a bunch of these apart and I trust him to spot differences. Of course, that's no guarantee he has correctly identified root cause. Perhaps there is just sample bias and the Delvac cars were just driven more/harder...

GTgears

No apologies required. I didn't take that personally. I was just trying to root out who these vested interests are. I think at the end of the day it's mostly oil manufacturers. Most shops have a personal favorite but it's often based on margins and not actual performance or results.

Ur20v

So money no object what is the highest performing gear oil for our GT cars- road and track?

Some of us don't do enough miles for the cost to become an issue within reason.

Sweeper

I only use Swepco

GTgears

Lubrication Engineers Synolec. Get some buddies together because smallest is a 5 gallon pail.

GTgears

Swepco 210 is an excellent choice as well.

John Chan

What about amsoil? I noticed 2nd gear grind when the car is not warm up compare to factory oil. Amsoil seems fine for track use and I am not complaining. But I have to warm up enough to drive out to street.
Synchro is not working well with cold amsoil in my experience.