mobilube PTX/ Porsche
- Thread starter dgjks6
- Start date
- Status
This Mobilube is basically a DCT/MTF GL4 oils with a lowish KV40*C that also claims GL5.
In axle application for components protecton , I would keep away from it and looking out for a 'solitary' GL5 of higher KV40*C or a grade viscosity higher.
Having said that, I'm not sure if Porsche brand matches this requirements.
In axle application for components protecton , I would keep away from it and looking out for a 'solitary' GL5 of higher KV40*C or a grade viscosity higher.
Having said that, I'm not sure if Porsche brand matches this requirements.
Originally Posted by dgjks6
The parts manual for my Porsche calls for mobilube PTX 75w90 in some places and Porsche brand 75w90 in others.
Are these the same fluid?
Which Porsche?
My '99 996 C2 Cab 6-speed called for the same (and that's what I dumped out of it at roughly 47k miles; factory fill by the looks and feel of it). I've spoken to several Indy shops with an online presence that tout Amsoil Severe Gear 75w-90 for the gearbox/diff (it's really a transaxle; the diff gears and gearbox share the same sump). However, I replaced the MobilLube PTX for Mobil Delvac 75w-90 with a shot of LubeGard's HD Gear Protectant....ran that for 10k miles....and am now on my second spill/fill for the same Delvac/LG HD mixture.
The fluid that came out was completely trashed (which I knew based on how it shifted). Thin. Putrid. Dark. And it had a slight metallic sheen. The Delvac that came out at 57K didn't look super great either, but it had a ton of stuff in suspension and it still nice and thick and slimey. Also, the gearbox was functioning far better.
So, my advice is that simply getting a temporary initial spill/fill to clean the innards out is VERY important to gearbox longevity. Possibly just as much as the gear oil used (as long as we're talking about the right stuff). The fluid upon sampling during this most recent fill it looks like honey, smells much better, and the car is just a joy to row through the gears in the hills by my home.
The Delvac/LG HD was an immediate improvement for me. Cold shifting got significantly easier (I have a short shift kit; so cold effort is naturally going to be higher) and shifting when hot turned to butter smooth. Whereas, with the FF, it was notchy and difficult when cold (often fighting me when trying to just go into 1st from a stop) and even worse when hot. Rev matched downshifts are now perfectly smooth and fast. And the LubeGard HD Gear Protectant, when added according to instructions, has done nothing but help the syncros (which now function perfectly).
Lastly, I always let all the fluids come up to full temperature before doing so, but I drive the car hard. Responsibly, but hard. The previous owners did not. And it shows; the car continues to run slightly better after each mile of my ownership.
And, for whatever reason, my car seems to have a preference for Chevron 93 w/ Techron over Shell V-Power 93 or BP 93 Amoco Ultimate according to both my fuel trims/ignition advance (via OBD Fusion on iOS), and my butt dyno. But every car is different....mine has not thrown any codes since I bought it at 44K miles.
The parts manual for my Porsche calls for mobilube PTX 75w90 in some places and Porsche brand 75w90 in others.
Are these the same fluid?
Which Porsche?
My '99 996 C2 Cab 6-speed called for the same (and that's what I dumped out of it at roughly 47k miles; factory fill by the looks and feel of it). I've spoken to several Indy shops with an online presence that tout Amsoil Severe Gear 75w-90 for the gearbox/diff (it's really a transaxle; the diff gears and gearbox share the same sump). However, I replaced the MobilLube PTX for Mobil Delvac 75w-90 with a shot of LubeGard's HD Gear Protectant....ran that for 10k miles....and am now on my second spill/fill for the same Delvac/LG HD mixture.
The fluid that came out was completely trashed (which I knew based on how it shifted). Thin. Putrid. Dark. And it had a slight metallic sheen. The Delvac that came out at 57K didn't look super great either, but it had a ton of stuff in suspension and it still nice and thick and slimey. Also, the gearbox was functioning far better.
So, my advice is that simply getting a temporary initial spill/fill to clean the innards out is VERY important to gearbox longevity. Possibly just as much as the gear oil used (as long as we're talking about the right stuff). The fluid upon sampling during this most recent fill it looks like honey, smells much better, and the car is just a joy to row through the gears in the hills by my home.
The Delvac/LG HD was an immediate improvement for me. Cold shifting got significantly easier (I have a short shift kit; so cold effort is naturally going to be higher) and shifting when hot turned to butter smooth. Whereas, with the FF, it was notchy and difficult when cold (often fighting me when trying to just go into 1st from a stop) and even worse when hot. Rev matched downshifts are now perfectly smooth and fast. And the LubeGard HD Gear Protectant, when added according to instructions, has done nothing but help the syncros (which now function perfectly).
Lastly, I always let all the fluids come up to full temperature before doing so, but I drive the car hard. Responsibly, but hard. The previous owners did not. And it shows; the car continues to run slightly better after each mile of my ownership.
And, for whatever reason, my car seems to have a preference for Chevron 93 w/ Techron over Shell V-Power 93 or BP 93 Amoco Ultimate according to both my fuel trims/ignition advance (via OBD Fusion on iOS), and my butt dyno. But every car is different....mine has not thrown any codes since I bought it at 44K miles.
Last edited:
When you say a "shot" of HD Gear Protectant, do you literally mean like a shot glass worth of fluid?
My '02 996 Cabrio has 41K on it. I replaced what I assume was the stock fluid at 40K with Pennzoil Synchromesh because the shift into third at high-RPM high-load conditions felt rubbery. Cold shifting felt smoother, but I noticed at an autocross that when the trans was good and hot, I had some trouble shifting into first and reverse. (I didn't shift into third at the autocross, so I didn't get to test that. And no I wasn't driving the track in reverse. LOL) So I ordered your concoction of Delvac 1 and Lubegard. The Lubegard stuff apparently only comes in a 32oz container, and it just felt kind of weird to use only 1oz of that and.. just put the rest on the shelf.
Last edited:
My quart of Lubegard Heavy Duty Gear Protectant arrived today. The bottle says to put in 3oz per quart of gear oil, so considering that the 911's 6-speed is supposed to take 2.7 quarts, I'll put in about 8oz. Unless anyone chimes in otherwise before I get the project done tonight. LOL
So, this was terrible. The 75W90 plus 8oz of Lubegard shifted worse than the Pennzoil Synchromesh. I had problems with the synchos in multiple gears. I dumped it after about 500 miles and bit the bullet on the $40/quart Porsche stuff. Shifting is back to where it should be now.
I'd use the recommended Porsche lubricant. I learned the hard way that the 996's (and 986) are, as rumored; finicky about their transaxle oil.
This Spring, I decided to try Redline in our 996 to replace the OEM fluid I had used 5 years ago. I've had good experiences with Redline to date. The Redline made the car very balky when cool and became noticeably notchy once warm. The feel wasn't horrible, but clearly wasn't correct. I switched back to the Porsche fluid by the middle of the Summer.
Yes the OEM fluid is $$, but it is what it is...
This Spring, I decided to try Redline in our 996 to replace the OEM fluid I had used 5 years ago. I've had good experiences with Redline to date. The Redline made the car very balky when cool and became noticeably notchy once warm. The feel wasn't horrible, but clearly wasn't correct. I switched back to the Porsche fluid by the middle of the Summer.
Yes the OEM fluid is $$, but it is what it is...
Mobil Delvac worked great in my 996.
Here is virgin analysis of mobilube 75w90
https://www.speediagnostix.com/new-oil-analysis/shc-75w-90
https://www.speediagnostix.com/new-oil-analysis/shc-75w-90
How was it compared to the OE? The Pcar forums are strong on the Delvac (not the standard Mobil1), and I was going to use that, though it isn't stocked in a lot of places near here. Then I drove by a Porsche dealer near a client and that was that.
The factory fill was ancient when I bought the 996 - I had no record of it being done. Castrol Syntrax 75W-90 worked well (dual rated GL4/5 and MT-1) and Delvac 1 was even better.
- Status