from the thread we all posted in Oct 2008.... Sorry to resurrect this but to jcthornes point the B - which is not what came with the GT's have shown break down ~3k miles. My son and I got into it about this and the resutls on SVT tell me to use T6 or Amsoil 10-40....
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WSS-M2C931-A is essentially SAE 5W-50 API SL. WSS-M2C931-B is essentially SAE 5W-50 API SM.
-A is GF-3 and -B is GF-4 [all honesty - I have no frigging idea what this means:facepalm:]
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10-23-2008, 07:46 PM
It is reported by some that running a *w-40 oil in the engine will cause a loss of power from less than full valve lift due to leak-down of the hydraulic lifters. I recommend only running oil meeting the Ford specs.
jack at accufab proved it! :thumbsup :cheers:cheers
BlackICE
10-23-2008, 07:49 PM
jack at accufab proved it! :thumbsup :cheers:cheers
It thought it was John at Accufab and Jack at Muscle Motors. :confused
RALPHIE
10-23-2008, 11:15 PM
Jack Roush ... which meets Ford WSS-M2C931-B....
http://www.roushoil.com/5w-50.html
Castrol ...Ford WSS–M2C931–A .....
Anyone familiar with the difference between "A" and "B" specs? Not sure I want to deviate from the "B" as it is specified for our gals. At least not until the warranty period is up.
MAD IN NC
10-23-2008, 11:19 PM
Anyone familiar with the difference between "A" and "B" specs? Not sure I want to deviate from the "?" as it is specified for our gals. At least not until the warranty period is up.
"?" was originally for the GT500's but now I believe I saw a post that A=B and that's all FoMoCo supplies :confused
Viper
10-24-2008, 08:47 AM
Thanks Neilda
But I f I had to deviate on the 5 or the 50 I guess I ought to deviate down on the 5?
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Indy GT
10-24-2008, 05:16 PM
This motor oil topic has been discussed many many times. Please do a Forum search on the topic. For our UK members expressing "difficulty" in getting the specific 5W-50 Motorcraft oil designed for the FGT engine, I have a hard time believing Ford or Rousch enterprises cannot get this oil which is now specified for both the FGT and the Mustang Shelby 500/KR engines. This oil is out there and as tmcphail posts, he can sell it to you if necessary.
The development and operating characteristics of our unique engines (and now similar offspring in the Mustangs) is premised on continued use of "good" oil being used. Using the factory recommended Motorcraft fluids is a no-brainer. You don't need to worry about warranty coverage, lubrication characteristics, batch-to-batch variation, viscosity selection, etc. It is all done for you. Ford recommends the use of THIS oil in our engines, and Ford continues to over-check production batches to ensure the product meets its lubrication requirements.
Unfortunately you can't go to Wal-Mart, Meijer, K-Mart, etc to buy the oil, and it does cost a bit more than other fully-synthetic oil offerings from say Red-Line, Penzoil, Amzoil, Moble-1, Royal Purple etc. If you can afford to spend $180K on a FGT, how can you reasonably support an argument to use a non-recommended lubricating fluid in the most expensive component of your GT? And WHY would you want to?? It just does not make sense.
Incidently Mike, the Ford WSS-M2C931-A spec (API service "SL") oil was the original formulation and comes with a "black" cap on the bottle. The newer WSS-M2C931-B oil (API service "SM") has reduced amounts of “ZDDP” wear resistant additive which has been linked to high mileage converter fouling and comes with a gold colored cap. I would think by now most of the "A" oil in inventory has been consumed as the switch to "B" oil was made quite some time ago. Both are equally acceptable in our engines and the newer "B" API SL oil has been reviewed (and tested) by the engine engineering team for acceptance.
Use the lubrication fluids Ford recommends for both the engine AND (very important) the transaxle as well. You will thus have much more time available to worry about something else.. (and your engine and transaxle will be happy). Note, I do not work for Ford nor do I have any financial gain in promoting the use of their fluids.
BlackICE
10-24-2008, 05:28 PM
Incidently Mike, the Ford WSS-M2C931-A spec (API service "SL") oil was the original formulation and comes with a "black" cap on the bottle. The newer WSS-M2C931-B oil (API service "SM") has reduced amounts of “ZDDP” wear resistant additive which has been linked to high mileage converter fouling and comes with a gold colored cap
If you could find old stock, the A (SL) spec oil it may be better than the B (SM) oil for maximum engine life at the expense of a possible reduction of CAT life.
Indy GT
10-24-2008, 06:23 PM
I understand your logic, and thought the same...
Although I believe it will be more difficult as time goes on to find any "A" oil remaining to use.
I have it on a reliable source, the "B" oil will work as fully intended in our engine application and has passed internal durability testing to support this conclusion. Use either will full confidence.
I think the reduction of ZDDP for catalitic converter fouling in our application is a "non-point". I would venture only "Seattle Jeff" will put the number of miles on his car to even think about converter fouling. Most of us owners will NEVER accumulate the miles necessary to approach this concern, nor will we ever fully utilize the fully synthetic Motorcraft oil attributes as we (at least I do) change the oil at very low mileage intervals and more on a "time" basis.
Thanks as always for your insightful comments!