Technical Data

From VanagonWiki

[edit] Fluids

[edit] Manual Transmission Gear Oil

VW specifies a 85W-90, API GL-4 rated gear oil. The transaxle has a capacity of 3.7 US Quarts (3.5 liters). GL-4 oils can be difficult to find, but many people have had luck finding CRC/Sta-Lube GL-4 at NAPA stores. Daryl of AATransaxle, a widely respected VW transmission rebuilder, recommends Redline MT-90, a synthetic GL-4 oil specifically designed for use in manual transmissions/transaxles.

There is some concern that using a modern GL-5 rated gear oil may be harmful to the manual transmission synchronizers. There is no reasonable basis for this concern. GL-5 oils are required to meet a higher level of performance than Gl-4 with regard to compatibility with the yellow (copper based) metals used in synchronizers. If the oil also carries an MT-1 rating, it is actually tested to an even higher standard.

GL-4 requires ASTM D-130 copper strip rating of 3B max. (after 1 h @ 121.1C).

GL-5 requires ASTM D-130 copper strip rating of 3 max. (after 3 h @ 121.1C).

MT-1 lubricants meet an ASTM D 130 requirement of 2A max. (after 3 h @ 121.1C). This is a more stringent requirement than that for GL-4.

The copper strip rating is determined by ASTM D-130 which is designed to assess the relative degree of corrosivity of the sulphur compounds contained in a petroleum product. The test is carried out by immersing a polished copper strip in a given quantity of sample, heating at a temperature and for a time characteristic of the material and comparing the copper strip after it has been washed and dried with the ASTM Copper Strip Corrosion Standards. The lower the strip rating, the better the result.

As far as wear capabilities the required testing is:

API GL-4, CRC L-20 API GL-5, CRC L-37 API MT-1, No requirement

These tests are for determining load-carrying, wear, and extreme-pressure characteristics of gear lubricants in axles under conditions of high-speed low-torque operation, followed by low-speed high-torque operation. L-37 is a more severe test.

Tests for thermal & oxidation stability/component cleanliness:

API GL-4, No requirement API GL-5, L-60-1 API MT-1, L-60-1

There are multiple other performance tests, all of which require a GL-5/MT-1 gear oil to perform better than a GL-4.

The principle area of concern is with regard to friction modifiers, which can determine how well the transmission shifts. Without a friction modifier, a GL-5 oil may actually be too slippery to spin up the synchros fast enough for good shifts. This will typically not be a problem on a Vanagon.

Added Mikes 14:23, 5 October 2007 (EDT)