Date: Tue, 28 Aug 2012 08:59:05 -0600
Reply-To: OlRivrRat <OlRivrRat@COMCAST.NET>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: OlRivrRat <OlRivrRat@COMCAST.NET>
Subject: Re: Gear box oil - Redline MT90 or Swepco ?
In-Reply-To: <503CB7B4.2070609@flatsurface.com>
Content-Type: text/plain; charset=US-ASCII; format=flowed; delsp=yes
Good info Mike ~ thanks for digging that up & posting it.
ORR ~ DeanB
On 28 Aug , 2012, at 6:21 AM, Mike S wrote:
> On 8/28/2012 3:10 AM, Gene P wrote:
>
>> 1) The German mechanic that installed a rebuilt transaxle for me 9
>> years ago said "use GL-4 oil only, NOT GL-4/GL-5, GL-4 ONLY. Wrote
>> it that way on the invoice. 5) A clip from a dandy 2-page technical
>> article on Redline's website: "GL-5 gears oils which are required in
>> hypoid differentials are not used in most synchromesh transmissions
>> because the chemicals used to provide the extreme pressure
>> protection can be corrosive to synchronizers, which are commonly made
>> of brass or bronze. Typically, the use of a GL-5 lubricant in a
>> synchromesh transmission will shorten the synchronizer life by one
>> half."
>
> This thread started with someone saying "don't use Redline MT-90..."
> based on a forwarded message where a friend of some person was talking
> to some other, unnamed person at Redline. Redline themselves says, in
> writing, about MT-90 "Popular in ... VW/Audi ... Safe for brass
> synchros
> ... Recommended for GL-1, GL-3, and GL-4 applications." That's us.
> Where
> it is not suitable, and they don't claim it is, is for a GL-5
> application. Redline recommends their 75W90NS gear oil for that, in
> the
> MTL/MT-90 spec sheet. It's odd that the forwarded "friend of a friend
> told me" post was saying "use the GL-5, not the GL-4," the exact
> opposite of what you usually see.
>
> Again, the GL-5 comments above don't apply to Redline MT-90, at all.
> But, regarding those comments, I believe this is where a lot of
> confusion comes from. GL-5 has greater extreme pressure lubricant
> requirements. Early formulations achieved that by using sulfur
> compounds
> which corrode yellow metals (synchros). They tend to smell really
> nasty.
>
> So, you will find people making blanket statements like "never use
> GL-5," because they're ignorant of the reasoning behind it. It's not a
> problem with GL-5, per se, but with _some_ GL-5 formulations. Many
> newer
> GL-5 formulas use additive packages which are no more corrosive than
> GL-4.
>
> GL-4 corrosion requirements are measured using a ASTM D-130 copper
> strip
> corrosion test. GL-5 does not have to meet this test. ASTM D-130 is
> designed to assess the relative degree of corrosivity of the sulfur
> 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. This produces a rating, where
> 1a=best, 4c=worst.
>
> Although GL-5 doesn't have to meet the test, the MT-1 spec (and
> MIL-PRF-2105E & SAE J2360) does require a D-130 test. The MT-1
> requirement is actually more stringent than the one for GL-4. The GL-4
> requirement is 3b after 1 hour, the MT-1 requirement is 2a after 3
> hours.
>
> So, if you're going to use a GL-5, it should _also_ carry one of these
> ratings. Such oils are not difficult to find.
>
> The other reason you may not want a particular GL-5 is shifting.
> There's
> a range of properties, etc. which fall into the 80W(-90) weight
> rating.
> Some oils are affected by temperature more than others. Some
> transmissions have a different shift feel than others. Various
> combinations produce different results. But, the same applies for GL-4
> oils, some just work better than others. I have MT-90 in mine, and it
> works for me. I know there are lots people who use it in newer VW/
> Audis,
> because it works for them.
>
> If you Google "MT-1 ASTM D130", you'll find lots of info (and some
> mis-info).
|