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TR2/3/3A Draining and refilling TR3 transmission with OD

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LexTR3 said:
A friend of mine who works in a Triumph shop up the road told me this morning that they use 40W Amalie oil because the lighter oil is better on the overdrive. Any thoughts on this?
Click to expand...
Lighter than what? The Amalie 40 weight is specified as 14.6 cSt at 100C, while the spec for 90 weight gear oil allows 13.5 to 24 @ 100C. In other words, the Amalie 40 weight meets the viscosity specification for 90 weight gear oil! So it probably works fine
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https://www.amalie.com/specs/1_pcmo.pdf
https://www.finalube.com/reference_material/API_Automotive_Gear_Lubricant_Service_Categories.htm

The hydraulic pump in an A-type OD has no seals or piston rings. Instead, it relies on a precision sliding fit between the piston and cylinder. If the oil becomes too thin at high temperatures, it can become harder for the pump to build and hold pressure, especially at lower road speeds (like 2nd gear where full pressure is most important).
<div class="ubbcode-block"><div class="ubbcode-header">Quote:]
Your mention of the Valvoline 20W-50 Racing Oil makes me think that this might be an excellent alternative to all the others. [/QUOTE]
It does work well, I used it for quite a few years. The "multi-viscosity" aspect allows for easier shifting while cold without thinning out too much at higher temperatures. It also has the advantage of being cheap and readily available.

But IMO the Redline MT-90 is a better choice. It is deliberately designed for better synchro operation (which should lead to reduced synchro ring wear, a common problem in TR gearboxes) and meets the GL-4 specification (so it provides protection for the thrust washers). It meets the specification for 90 weight gear oil (15.6 cSt @ 100C), while the high viscosity index helps prevent the "stirring molasses" effect in cold weather.
https://www.redlineoil.com/product.aspx?pid=46&pcid=7

It made a noticeable improvement in my TR3 (which has a late TR6 gearbox with a TR4 overdrive); I have no intention of switching back or trying anything else.

Several people have commented that it even covered up their worn synchro rings; letting them shift without clashing or double-clutching.
 
Hmmmm. So, the Amalie 40 weight is essentially the same as the 90 weight hypoid gear oil. Your added comments about 20W-50 racing oil as allowng for easier shifting while cold without thinning out too much at higher temperatures makes it sound like a good choice. I will also check out the Redline MT-90.

How does the MT-90 compare with NAPA Premium Performance hipoid gear oil, SAE 80W-85W-90? If there's not much difference, I go with this (or the "equivalent" Amalie 40) as they are relatively easy for me to obtain here in the country in the Shenandoah Valley.
 
LexTR3 said:
So, the Amalie 40 weight is essentially the same as the 90 weight hypoid gear oil.
Click to expand...
No, no, wait a minute. There is a whole lot more to oil than just viscosity/weight. I only said the weights were similar. Maybe this will clarify a bit (although it still doesn't talk about coefficient of friction, detergents, anti-foam, etc):
https://www.volvoclub.org.uk/gear_oils.shtml
<div class="ubbcode-block"><div class="ubbcode-header">Quote:]How does the MT-90 compare with NAPA Premium Performance hipoid gear oil, SAE 80W-85W-90?[/QUOTE]I don't have any direct knowledge, but I am going to guess that, since the NAPA product is a relatively inexpensive conventional gear oil, it both uses the 'bad' sulfur-based additive, and is not optimized for use in synchromesh transmissions. That would make it inferior to everything we've discussed here, IMO.
 
The bottom line, it seems to me, is that MT-90 75W90 GL-4 Gear Oil is the product to use. It doesn't have the sulfur that works on brass, and it satisfies the gear oil viscosity requirements of 75W,80W and motor oil viscosities of SAE 40, 10W40, and 15W40. It is recommended for GL-1, GL-3, and GL-4.

I am going to keep the Amalie 40W currently in my car until I reach 5000 milies since putting it in, and then switch to Red Line MT-90.
 
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