Mineral vs Synthetic for synchro performance

[FTO-UK]

Having done a little research on the Internet it seems that many vehicle owners/technicians avoid the use of synthetic gear oils because they are 'too slippery' for good sychro performance. They prefer mineral gear oils, which they claim give better synchro 'bite'. I am aware that good quality synthetic MTL's are friction modified - but I wonder how these compare in terms of sychro performance to regular mineral MTL's.

I've also seen comments from drivers who say that using a synthetic has 'ruined' their synchros (i.e. they put synth MTL in and the gears started to grind - this effect was then not reversed by going back to a mineral oil).
In short, might we be better to stick with a mineral oil in our manual transmission.....?

 

[theguru]

What you need to do is put the right oil in your mt. By right I mean the one which will give the best changes and best life.

In general synthetic will give longer life to the oil and better high and low temperature performance.

The wrong dino oil will give poor changes etc as much as any synthetic.

The best oils can't make up for worn gearboxes, but they may improve them. Also some gearboxes are just poor changes - full stop. Part of the original design.

 

[Bror Jace]

It's not the matter of 'mineral' vs. 'synthetic' base oil but much more a function of the additive package in the lubricant: including EP (Extreme Pressure) & AW (anti-Wear) agents and especially friction modifiers.

Do a search of this subsection using the words "syncromesh" and "synchronizers."

--- Bror Jace

 

[JohnBrowning]

Also search GL3,GL4 and GL5 these topics discuss this in detail. It is not so much the base stock as the additive chemistry.

 

[Gurkha]

Switching from dino tranny oil to synth made a huge difference in overall perfomance of my trannies, shifting, smoothness as well as noise level were all improved and so did the drain intervals, synth is definitely worth it, must for diffs.

 

[TooSlick]

FTO UK,

Well, many people on the Internet haven' got a clue what they are talking about, but that doesn't keep them from pretending they do.

I've been using synthetic gear lubes since 1978 and synthetic ATF since about 1987 or so. I honestly haven't seen any issues with either type of product.

Ted

 

[Schmoe]

On Fords, if they took the time to put a synthetic only stamp on the rear end, I'd surely be sticking with it.

 

[mechtech]

You can have a synthetic with more 'bite' for the synchros than a dino lube.
Viscosity and friction modification are key elements.

 

[Whimsey]

For my 1996 Contour/Mondeo 5speed I went from mineral AFT to Ford's synthetic tranny fluid. I believe the tranny is the MTX-75. Works 1000% better than the mineral fluid. 35,000 miles later no problems and it still shifts good in all temps. Though I am going to use Mola's SF tranny fluid shortly. i just haven't decided which one yet

.

Whimsey

 

[SilverGGA@Work]

I've read enough experiences regarding this subject on Subaru forums that I feel that the inherent low friction of synthetic fluids (compared to dino) do make a difference in synchro performance.

The WRX transaxle requies 75w-90 GL-5. Many people have used Redline 75w-90NS and experienced grinding synchros. They then switched back to plain Valvoline dino 75w-90 and everything was back to normal.

Redline 75w-90NS has no friction modifiers for limited slip and is the recommended fluid to use in a transmission when 75w-90 GL-5 is required. While the Valvoline dino is just a general gear lube not made specifically for transmissions.

Many others have equally bad experiences with Mobil1, Royal Purple Max Gear, and Motul etc... but arguments could be made that those had limited slip additives and therefore were not optimal for synchro performance.

This is why I single out Redline as an example.

In short, I believe the inherent low friction property of synthetics do make a difference in synchro performance. However, with a well-designed box, or a very careful driver, or well-picked additives, can usually override this difference. But, in a sensitive box like the one in the WRX, the difference may be significant enough to affect the choice of fluids.

 

[slider]

Originally posted by FTO-UK:

I've also seen comments from drivers who say that using a synthetic has 'ruined' their synchros (i.e. they put synth MTL in and the gears started to grind - this effect was then not reversed by going back to a mineral oil).

***

In my 99 Escort 5 speed manual, which specifies ATF, I first tried Mobil 1 ATF and the synchros on the 2-3 shift started grinding on quick shifts. Changing to Redline MTL wasn't any different. I then installed Redline D4 and while the problem was reduced, it didn't go away, but it was minimal and so I left it in. (I usually don't shift quickly) After about 5K miles, all synchro grinding problems went away.

I've since gone back to plain Chevron ATF with no grinding problems at all. I'm inclined to continue with plain ATF, but I might try the Specialty Formulations MTF glide to extend intervals, as changing the fluid in this trans is typically very messy and I therefore dislike doing it.

I would prefer to use a synth as plain jane ATF starts to turn dark after aobut 10K. The Redline D4 was still bright red even after over 20K.

Believe it or not, Ford doesn't recomend ever changing the fluid! Can't agree with that, given how regular ATF turns dark after 10K. Synth can obviously go much longer, but I don't want grinding.

 

[MolaKule]

I think you'll find our MTFGlide (a GL4) is almost as good as greased lightning.

Most ATF's have AW/EP protection levels of GL2 at the most.

 

[Bror Jace]

SilverGGA@Work: "In short, I believe the inherent low friction property of synthetics do make a difference in synchro performance. However, with a well-designed box, or a very careful driver, or well-picked additives, can usually override this difference."

That's why I'd only use a fluid designed specifically for synchros in a synchromesh transmission.

Best to use a fluid which is properly friction modified for the job, whether it have a mineral or synthetic base oil.

So, that'd be Red Line MT-90 (I know it's 'only' a GL-4) or Specialty Formulations MTL-R (which is GL-4/5).

--- Bror Jace

 

[Mike_dup1]

quote:

---

Originally posted by FTO-UK:
Having done a little research on the Internet it seems that many vehicle owners/technicians avoid the use of synthetic gear oils because they are 'too slippery' for good sychro performance. They prefer mineral gear oils, which they claim give better synchro 'bite'. I am aware that good quality synthetic MTL's are friction modified - but I wonder how these compare in terms of sychro performance to regular mineral MTL's.

I've also seen comments from drivers who say that using a synthetic has 'ruined' their synchros (i.e. they put synth MTL in and the gears started to grind - this effect was then not reversed by going back to a mineral oil).
In short, might we be better to stick with a mineral oil in our manual transmission.....?

---

There are many forums on the internet and these are often the result of seemingly knowledgeable persons offering so called "expert information" to those that aren't.


Experts Don't Always Know What They Are Talking About.


I have synthetic ATF in my Tremec 6 sp trans since 2001, no problems whatsoever. 99% of all the negative things about synthetic lubes boilds down to cost. While many think the cheapest lubes are just as good as the synthetic, when it come to medicine and someone (ins) else is paying, they don't want generic do they?

[ April 23, 2005, 09:42 AM: Message edited by: Mike ]

 

[SilverGGA]

Same here. SF MTL-R 75w-90 GL-5 will be going in my WRX when my next change is due.

quote:

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Originally posted by Bror Jace:
SilverGGA@Work: "In short, I believe the inherent low friction property of synthetics do make a difference in synchro performance. However, with a well-designed box, or a very careful driver, or well-picked additives, can usually override this difference."

That's why I'd only use a fluid designed specifically for synchros in a synchromesh transmission.

Best to use a fluid which is properly friction modified for the job, whether it have a mineral or synthetic base oil.

So, that'd be Red Line MT-90 (I know it's 'only' a GL-4) or Specialty Formulations MTL-R (which is GL-4/5).

--- Bror Jace

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