Let me start by telling you that Gear Oil’s are not Transmission Oils. Transmissions have gears and synchronisers. These of which require a different additive package. If you are wondering if GL5 covers GL4 the answer isnt simple. GL5 covers GL4 in terms of protection, but contains to much detergent and will strip any white metals and strip any brass synchronisers.
Simply, GL4 gear oils are intended for axles with spiral bevel and hypoid gears operating under moderate to severe conditions of speeds and loads. GL-4 gear oils also have a low detergent level, which help protect yellow and phosphorous metal elements of the gear box. You can use GL-5 for high-speed loads and also for low-speed torque systems without yellow metals.
Putoline GP80 is sold as motor cycle gear box oil and is GL4, 80W.
The Ariel owners guide states use of SAE 50 or 60
If your gear box is seizing up at tick over it is not a cause of the gear box oil, unless you are using 2 stroke oil in it!
Last edited by Thoward
on Wed Dec 30, 2020 1:36 pm, edited 1 time in total.