Gearbox / Engine Oil Additive

[Zilli]

I thought i would start a discussion regarding engine/gearbox oil additive, given that we have a myriad of threads regarding what oil to/not to/recommended use etc. Understanding this might be quite an opinionated discussion, i ask anyone who wants to respond here to actually have some sort of information or experienced base to discuss it, rather than mentioning what you mechanics sister's dog said is good or not.

It's a pretty big industry, and i've had discussions with a mechanic mate of mine who races cars/karts/bikes who swears by a range of Nulon products that he adds to his oils at all times. His view is they reduce wear, and improve performance (less drag, easier shifts etc).

The reason why i want some opinions and views is

1) Our cars are getting a bit long in the tooth, some of us have over 100k kms on our cars
2) Our cars are quite sensitive to the quality/viscosity/frequency of oil changes
3) Our cars are usually driven in anger, hopefully always in a controlled environment, due to their high revving nature and a need to be on top of things to get them going as fast as they can

My particular interest is in maintaining my gearbox... as i can be quite rough on it, and whilst it is still in perfect condition, the picky bastard in me wants to make sure it absolutely stays that way... i do a gearbox oil change (MTF) every second engine oil change which is usually over 5000kms.

Thoughts?

[aaronng]

You use FEO as gearbox oil?? Why not MTF?

[Zilli]

my bad... :-) i meant MTF

[aaronng]

What engine oil do you use? My opinion is that if you have a cheap engine oil, then additives can work by delaying viscosity changes. But if you use a mid-range to upmarket oil, then the additives actually work against the existing additive package in those oils. The question that I would pose to someone using FEO + Nulon is "why not buy a better and more expensive oil in the first place if the total cost and performance/protection is the same?"

[Zilli]

tried Royal Purple, but going back to Mobil 1 Supersyn in the motor... MTF in the gearbox

[aaronng]

tried Royal Purple, but going back to Mobil 1 Supersyn in the motor... MTF in the gearbox

If you are using Mobil1 Supersyn (gold bottle I assume), then adding Nulon additives to it would be a downgrade! If you had some cheap oil like MTF, Magnatec or the Mobil Synth S, then yeah, it would be worth adding Nulon. But if you already have Mobil 1 Supersyn, then it's like adding tomato sauce to some high class food that tastes so good that you get an orgasm with each bite. You get what I mean?

[Zilli]

absolutely!

what about gearbox fluid though? the way that i see it, a motor will loat longer given the reasonably due care is taken in the way it is used, and maintained

A gearbox leaves many more variables though, if you did the appropriate maintenance etc it should be fine, but in a given circumstance, let us say on the track... racing for 20 laps at 10/10ths you gearbox would see more wear than your motor in my opinion (the quality of lubricants i would assume as a constant, as they would both be the best money would buy?. I assume the gearbox would see more wear simply because it is being manipulated by the revolutions of the motor AND the hand that is using it...

So my question is, can the logenvity of the gearbox be prolonged using additives along with fresh MTF regularly? or would just regular fresh MTF suffice, and the additive would do nothing?

[JohnL]

Zilli,
I agree with aaronng, use a good oil in the first place and forget about additives (that in all probablity may well make a good oil worse). If you're really serious (and can afford it) then you can't do better than the various fully synthetic oils such as Redline, Motul, Royal Purple or Mobil 1 Supersyn (the real Mobil 1, not the other Mobil 1 which is only a marketing exercise basking in the Supersyn reputation) etc.

A significant chracteristic of high quality synthetic oils is that they are inherantly so good that they require very little if anything in the way of additive packages.

With the gearbox, again the best oils will in all likelihood be damaged by ad-hoc additives. I use one of the Motul synthetic gear oils in my high mileage box, and I have no complaints (shift quality is noticably better than with the OE oil, probably engine oil). You do need to make sure that you use an oil designed to be compatible with synchromesh, some are designed for racing 'crash' boxes (i.e. no synchro) and can be so slippery the synchromesh won't work properly.

Gearbox oil can be left unchanged for a very extended period because there are no combustion by-products to degrade it. The main reason you'd need to change it would be to remove possible metallic particles. A magnetic sump plug is a very good idea in a manual gearbox to catch any ferrous particles.

However, if you use an engine oil (in the gearbox) that has additives that are 'long-chain polymers' then this needs to be changed much more often due to the oil shearing action of the gear teeth sliding against each other under load.

This literally tears apart the 'long chains' of atoms in the additives, turning them into 'short-chain polymers', which don't have the same beneficial tribological characteristics as long chain polymers.

This is the main reason why oil should generally be changed at very short intervals in high performance BMC Mini engines (and short intervals in non high performance), i.e. because the oil is both the engine oil and gearbox oil, and thus it is both 'polluted' by the combustion products as well as being 'shredded' by the gears (the main reason why having the gears in the engine sump isn't such a good idea).

If you're interested in oil and additives etc etc etc, then have you come across the 'bobistheoilguy' website?

absolutely!

what about gearbox fluid though? the way that i see it, a motor will loat longer given the reasonably due care is taken in the way it is used, and maintained

A gearbox leaves many more variables though, if you did the appropriate maintenance etc it should be fine, but in a given circumstance, let us say on the track... racing for 20 laps at 10/10ths you gearbox would see more wear than your motor in my opinion (the quality of lubricants i would assume as a constant, as they would both be the best money would buy?. I assume the gearbox would see more wear simply because it is being manipulated by the revolutions of the motor AND the hand that is using it...

So my question is, can the logenvity of the gearbox be prolonged using additives along with fresh MTF regularly? or would just regular fresh MTF suffice, and the additive would do nothing?

[Zilli]

good info... ive long been tempted to try a different fluid for the box, but there are so many conflicting stories. The reason why i hold back is because the car is essentially for street use, and even then it doesnt get driven much... i dont want to be putting in a higher grade "race" oil whish is designed to protect in high heat conditions because it will rarely be put in that position.

What i do want, is the best that money can buy, to ensure the longevity of the hardware...

[aaronng]

absolutely!

what about gearbox fluid though? the way that i see it, a motor will loat longer given the reasonably due care is taken in the way it is used, and maintained

A gearbox leaves many more variables though, if you did the appropriate maintenance etc it should be fine, but in a given circumstance, let us say on the track... racing for 20 laps at 10/10ths you gearbox would see more wear than your motor in my opinion (the quality of lubricants i would assume as a constant, as they would both be the best money would buy?. I assume the gearbox would see more wear simply because it is being manipulated by the revolutions of the motor AND the hand that is using it...

So my question is, can the logenvity of the gearbox be prolonged using additives along with fresh MTF regularly? or would just regular fresh MTF suffice, and the additive would do nothing?

My opinion is change your MTF after every trackday. MTF can last about 4-5 years with normal street driving. That's about 80,000km if you go by the 6 month = 10000km estimate.

I change MTF every 2 years for street driving and/or after every 2 trackdays. Granted my car is only 5 years old and has 80,000km on the clock, I did go for 5 trackdays. 4 of those were at Wakefield which works out to be about 90 minutes worth of on track time for each day and would equate to 360 minutes in total (240 laps at 1:30 per lap) running only on pure transmission fluid without additives. My gearbox still shifts smoothly and goes into gear at any RPM without problems. For the life of my car, I have changed MTF 3 times.

[Zilli]

hmmmm... maybe i'm being too fussy... mines 00 with 70k km's and still shifts beautifully...

I suppose my question is answered though... just stick to good quality fluids...

Seems like there is zero merit to additives...

[JohnL]

For the life of my car, I have changed MTF 3 times.

My CB7 had 206,000 km on the clock when I bought it. From the comprehensive service history containing no record of a gearbox oil change, my bet is that it probably had the same gearbox oil as it did on the day it was driven out the factory gate. I soon changed it to the Motul oil which I plan on changing at 300,000 km.