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GL5 vs. GL4 Gear Oil for Transmission

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Old 08-11-2017, 09:54 AM
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Originally Posted by TeamRX8
Ford Motorcraft XT-M5-QS

Just stirring the conversation - but I switched to this stuff from Pennzoil Synchromesh(which was also great, was due for a change) last summer and ever since I have had a lot more transmission whine. Transmission shifts great and feels fine - but the whine is an interesting side effect for me. Anyone else experience this as well?

Transmission is still original at 102k miles, but I just find it odd that I noticed it immediately after switching fluids over.
Old 08-11-2017, 11:36 AM
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Originally Posted by Darkning
Just stirring the conversation - but I switched to this stuff from Pennzoil Synchromesh(which was also great, was due for a change) last summer and ever since I have had a lot more transmission whine. Transmission shifts great and feels fine - but the whine is an interesting side effect for me. Anyone else experience this as well?

Transmission is still original at 102k miles, but I just find it odd that I noticed it immediately after switching fluids over.
That be the good stuff though I didn't use this yet. I stuck with MT-90 on the change from factory at ~ 40K miles (first change).
Old 08-11-2017, 02:32 PM
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Whine is usually worn internal bearings which is common on an S1 trans with moderate or more use/miles, first time I heard someone thinking this oil resulted in it though

Edit: 102k, yeah that's bearings and it never should have had synchromesh fluid in it in the first place




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Last edited by TeamRX8; 09-20-2017 at 10:31 AM.
Old 10-03-2017, 08:42 PM
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Originally Posted by TeamRX8
Whine is usually worn internal bearings which is common on an S1 trans with moderate or more use/miles, first time I heard someone thinking this oil resulted in it though

Edit: 102k, yeah that's bearings and it never should have had synchromesh fluid in it in the first place




.
Yeah, that's what I was thinking. The whine begin with the fluid change, which might just mean a change in general was the culprit and not the oil that I put back in. Losing the viscosity of the old oil that probably had some metal particles floating around to thicken it up a bit is probably why it wasn't as noticeable before the change.

Edit: on topic of Synchromesh though - I know a couple people who have gone almost the entire 100k life of their transmissions with the Synchromesh fluid to no ill effects.
Old 10-06-2017, 10:18 AM
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Just for conversation's sake, here's my experience.

Rebuilt the motor in the 8 a total of 3 times, it's a long story, and have had Amsoil 75w-90 Long Life gear lube in the transmission for about 6,500 miles. I found that I didn't like the way the transmission shifted, it would grind upon hard acceleration shifting, and didn't want to downshift into 1st at all and 3rd and 2nd weren't much better. This is a GL-5 fluid designed for differentials but I figured it didn't matter for an old(er) transmission.
Fluid PDF: Amsoil 75w-90 Long Life gear lube

Swapped it to Amsoil 75w-90 Manual Transmission fluid and it seems to be doing much better. Smoother shifts, better downshifts, no grinds on hard acceleration shifting. This is a GL-4 fluid designed for manual transmissions and transaxles. It's been in the car for about 1,000 miles now and I feel like it is doing much better.
Fluid PDF: Amsoil 75w-90 Manual Transmission gear lube

I'm not an Amsoil fanboy. I just buy it because I get it cheaper than parts store fluid now that I'm a dealer, and only buy it for myself. When you're maintaining a Saturn, Suburban, Audi Allroad, RX-7 and RX-8 fluid adds up quickly and gets super expensive. Any way to save money is a good way!
Old 10-06-2017, 10:51 AM
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Originally Posted by DreamInRotary
I'm not an Amsoil fanboy. ...now that I'm a dealer...
Old 10-06-2017, 11:45 AM
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Originally Posted by NotAPreppie
Reread the post, spelled it out pretty plainly:

I just buy it because I get it cheaper than parts store fluid now that I'm a dealer
I wouldn't buy it if it wasn't cheaper than parts-store prices. I used to run Mobil-1 products forever in my nicer vehicles, Valvoline in the ones I didn't care so much about. I still use Mobil-1 oil filters when I can't get the filters I want/need.
Old 10-06-2017, 12:09 PM
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You claim to not be biased in favor of a product you sell... ¯\_(ツ)_/¯
Old 10-06-2017, 12:14 PM
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Originally Posted by NotAPreppie
You claim to not be biased in favor of a product you sell... ¯\_(ツ)_/¯
This is throwing the thread way off topic, but I'll respond anyways for clarification.

I do not sell Amsoil, I just use it at home for personal projects. I've never sold it to anyone else, I just hold the "Dealer" title in order to get it cheaper for myself. So I am not biased towards it, I just use it because it's cheaper than the parts store fluids. I used to, and still use, Mobil-1, Castrol, Pennzoil, and Valvoline products when necessary.
Old 10-06-2017, 04:10 PM
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I like it and did the same a long time ago. Just too much of a bother to order and ship it imo.

If I said it once, then this must be the millionth time; oil brand etc. is way over-rated and mostly marketing schlock driven.
Old 10-06-2017, 08:11 PM
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Originally Posted by TeamRX8

If I said it once, then this must be the millionth time; oil brand etc. is way over-rated and mostly marketing schlock driven.

Well I did forget one exception, and that’s the Motorcraft GL4 trans fluid. Still haven’t found anything else as good at proving that snickety-snick gear shift feeling, bwa-hahahahaaaaa ...
Old 09-18-2018, 05:56 AM
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Definitely GL4 for gearbox for series 1 Wonder if Mazda changed it to GL5 for series 2 ?
Old 09-18-2018, 06:29 AM
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2004/2005 it was GL-5 for the gearboxes.
2006+ they changed it to GL-4.

Didn't change the gearbox; just the oil spec.
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Old 09-18-2018, 06:43 AM
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Originally Posted by NotAPreppie
2004/2005 it was GL-5 for the gearboxes.
2006+ they changed it to GL-4.

Didn't change the gearbox; just the oil spec.
thanks but gearbox was changed for series 2 ?
Old 09-18-2018, 07:16 AM
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Originally Posted by Sydo


thanks but gearbox was changed for series 2 ?
Yah, but the spec didn't change.
Skip to page 10-4.
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Old 09-18-2018, 11:47 AM
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My transmission whines, 89k miles. I'll change the fluid out for a fresh GL4 soon. Long term I plan to move to an S2 gearbox.
Old 09-18-2018, 04:11 PM
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Originally Posted by NotAPreppie
2004/2005 it was GL-5 for the gearboxes.
2006+ they changed it to GL-4.

Didn't change the gearbox; just the oil spec.
Is it plausable Mazda made a blunder recommending GL5 in early series 1 considering they changed to GL4. This would have caused premature wear
Old 09-18-2018, 05:15 PM
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Originally Posted by Sydo

Is it plausable Mazda made a blunder recommending GL5 in early series 1 considering they changed to GL4. This would have caused premature wear
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