... or is it more of a everyone uses gl-5 so just use that kind of a deal?
That's what everyone I know is using.
Those guys on TheSamba are so ignorant it's not funny. They quote their 30 year old Bentley manual that states you must use GL-4, when GL-5 didn't exist. Well, guess what, GL-5 is on the way out, GL-6 is the new rating.
This fearmongering is only rampant in the VW world. If you look at the manual transmission in any Honda, Toyota, Ford, Chevy, Dodge, Volvo, BMW, Porsche, etc., they all use brass syncros just like your VW. Ask any authorities in their camp and you'll discover they've never heard of this \"problem\".
Go online to any oil company's web site. Find a contact and send a question to their tech support. You'll get the same answer I got from Amsoil, and Glenn got from Swepco. GL-5 with the MT-1 rating is perfectly safe for any gearbox with brass syncros.
Do you believe the oil companies would produce a product that would destroy your gearbox? In reality, they are all in competition to provide you with the best product they can for the best price. If there was a risk of damage, there'd be a warning on the label, \"not for use in VW gearboxes\" or something like that. Have you seen such a warning? Go and look at the ATF, you will see plenty of warnings. Fords must use F type ATF. Look at the antifreeze. You have pink, green, blue. You must use the right stuff for your car. I've never seen any warnings on any gear oil.
I have challenged the ignorant fearmongers to show me one single brass part that has damage from using GL-5. They can't come up with one single case.
What's the difference you ask? GL-5 has a much better extreme pressure rating than GL-4. To achieve this requires higher sulphur content. Problem is, sulphur is corrosive to brass at really high temperatures. However, the American Petroleum Institute knows this, so they came up with a formulation to prevent corrosion at any temperature. This extra formulation has a designation MT-1. All GL-5 has the MT-1 rating, making it perfectly safe for use in gearboxes with brass syncros. If you have a gearbox mated to an engine that puts out more than stock hp, you must use GL-5 to get the superior extreme pressure protection. I have seen plenty of spider gears and side gears that were literally worn out from using gear oil with inferior EP protection over the last 40 years.
Don't waste your time looking for the 8-track of gear oil. Just like engine oil, today's gear oil is far better than what you could get 30 years ago. Embrace modern technology.
