Well just a follow up, since nobody could provide any good information on additive packages effects I ended up going with Redline Synthetic 75W-90 and it seems to be working but it is a compromise of better shifting performance for less gear protection.
Mobile Delvac/Synchromesh VS. Amsoil MTG 75/90 for G56
- Thread starter 2009ram2500
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Wanted to update this thread.
O2SE...You where right! Part of the problem was overfill beyond the acceptable extra, see below.
Drained the Amsoil MTG and found out that it was overfilled by about a quart to quart & a half OVER my overfill. So my 7.5 quarts was actually 8.5 to 9 quarts and the oil severely airated and that's why I had such tempature increase because it wasn't lubricating the gears especially under load.
FYI, use the rear drain plug on the bottom to drain the trans NOT the side inspection plate as it leaves about a quart to quart & a half in the transmission.
I did change out the Amsoil MTG with the redline MT90 75w-90 and have been happy so far. The shifts are smother, it still sticks getting it in and out of gear but it's much better than Amsoil MTG ( that's been airated). The redline is a little thin for me but it seems to work, it does warm up under load but it's maxed out about 210*F going up white water with 8k in tow in the power in 6th (over drive) in 85*F ambient (And it did recover back down to 190 in about 10 miles.).
From this experience I'm 99% sure the original Mobil Delvac/ synchromesh mix was over filled with at least a quart of ATF from the original fill since I did that removal through the side inspection plate also BUT that held up much better to the abuse /airration better than anything else and still kept temps much lower.
All in all I think the Mobil Delvac SAE 50 transmission fluid/ Amsoil Synchromesh mixed at 5 quarts Delvac to 3 quarts Synchromesh is the best fluid I've ran so far. I did have shifting issues with it that where getting worse but I'm not sure it it was the fluid , or if it was some interaction with the left over ATF or airation??? This combo had the best protection, the best ability to keep temps way down, and fight airation.
At this point I will be keeping the Redline MT90 75w-90 in the trans as it's working good, it just does not keep the temps as low as the Delvac/Synchromesh combo did, to me this means less protection BUT does go in to and out of gear better than the Delvac/Synchromesh combo, so it'll stay for at least for the next 25k.
On a side note, I kept all of my old oil from all of these changes so if someone has a Blackstone account I'd be very interested in submitting a sample of the Mobil Delvac SAE 50/Amsoil Synchromesh combo for anaylsis including sulphur ( which is an add on to standard VOC test at Blackstone) to see how this mix compares to the other options and see if there are any adverse effects by combining these two?
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Thanks for update OP.
Did you not 'overfill' RL this time round ?
Redline MT 90 is not thin, it's thicker than Amsoil MTG at 45*C upwards and thicker than 5/3 blend at 50*C upwards, which forms close to 95-98 % (?) of your operating regimes.
It's interesting to note a thicker MT 90 operates 'cooler' than a thinner Amsoil MTG 75W90, so much for advocating otherwise often times.
Granted, physics in frictional drag losses is physics.
Hence, the so called potentially increased 'aeration' ferocity attributing to 'overfill' ,has no bearing on increased rate of heat generation and fluid temperature increase in 'overfill' , if it matters .
As suggested by several posters above, you may want to consider MT-1 Mobil Delvac Transmission Fluid SAE 40.
In your operating conditions, I wouldn't be surprised if this Delvac 40 delivers you improved performance in temperature drop vis-a-vis 5/3 blend , I have no doubt it's more appropriate for your 'demands' .
Yes, MT 90 at 15.6 cSt (210*F) offers far less components protection in relation to 5/3 blend at 20.0 cSt (185*F).
Would the suggested Delvac SAE 40 performs better than 5/3 blend above in terms of operating temperature and operating viscosity ? I would speculate so, if perceptible.
Would it perform worst than the 5/3 blend or RL in shifting ? I would think not necessary so, in practice. Only OP can demonstrate such.
Originally Posted by 2009ram2500
I did change out the Amsoil MTG with the redline MT90 75w-90 and have been happy so far. The shifts are smother, it still sticks getting it in and out of gear but it's much better than Amsoil MTG ( that's been airated). The redline is a little thin for me but it seems to work, it does warm up under load but it's maxed out about 210*F going up white water with 8k in tow in the power in 6th (over drive) in 85*F ambient (And it did recover back down to 190 in about 10 miles.).
Quote
From this experience I'm 99% sure the original Mobil Delvac/ synchromesh mix was over filled with at least a quart of ATF from the original fill since I did that removal through the side inspection plate also BUT that held up much better to the abuse /airration better than anything else and still kept temps much lower.
Quote
All in all I think the Mobil Delvac SAE 50 transmission fluid/ Amsoil Synchromesh mixed at 5 quarts Delvac to 3 quarts Synchromesh is the best fluid I've ran so far. I did have shifting issues with it that where getting worse but I'm not sure it it was the fluid , or if it was some interaction with the left over ATF or airation??? This combo had the best protection, the best ability to keep temps way down, and fight airation.
Quote
At this point I will be keeping the Redline MT90 75w-90 in the trans as it's working good, it just does not keep the temps as low as the Delvac/Synchromesh combo did, to me this means less protection BUT does go in to and out of gear better than the Delvac/Synchromesh combo, so it'll stay for at least for the next 25k.
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MolaKule
Staff member
Originally Posted by 2009ram2500
Ok so I've got some new information that could use some clarification on.
1) I've read that Sulfur eats copper alloys including brass, AKA sulfur eats brass synchros, id this correct?
Originally Posted by 2009ram2500
2) I was told be a tech at Mobil that Delvac 1 Transmission Fluid 50 has a GL-4 sulfur based EP additive package in it BUT I if you read Mobil's website it specifically states that this fluid is GL-4 NON EP with no sulfur based additive package. Assume the tech is just wrong here?
Originally Posted by 2009ram2500
2) 3) What does 4,000+ PPM Magnesium do for the transmission?
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Zeng, Viscosity is all about the same according to their SDS/MSDS. There all right about 86/14-15 Cst.
And I know the MTG was airated severely, as when i came out there where tons of bubbles/foam in it through I hadn't moved the vehicle in at least 3 or 4 days. I had to wipe the foam off the gears. Plus the symptoms makes sense now, put it under heavy load it'd heat up 30-40 degrees, it heated up much faster than the previous oil under regular load, basically the oil was not coating the gears and therefore it could not remove the heat from the metal. Gear oil is a much better conductor or heat than air.
As for knowing if I overfilled it this time; I discovered I over filled it when I removed the inspection plate drained it this time, then decided to remove the actual drain plug and to my surprise another 1-1.5 qts came out AFTER I thought I had gotten it all out through the side inspection plate (time before I did NOT remove the drain plug just the inspection plate), plus I measured what I captured coming out an it was 8.5 qts plus I lost some on the drain.
Since I dropped the drain plug this time I know I got it ALL out before I refilled it with the Redline MT90 and when it went in I was very carefully to measure a predetermined amount to achieve the fill I wanted.
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