Oil for dog box

[PaulFinch]

Hello All,

About to install a newly built gearbox with a brand new quaife dog engagement gearset.

The builder has recommended a 75/90 GL4 spec oil but from what I've read and heard about, a GL5 spec oil such as redline shock proof would be more suitable. Any one have any specific recommendations?

Thanks as usual.

Paul

[patrics]

Hi Paul,

I intend to use this Millers oil in my gearbox

CRX 75w140 NT Fully Synthetic Motorsport Transmission Oil

I did try Redline last year but my once good original Lotus Cortina gearbox only last about 10 minutes of qualifying before 1st gear welded its self to the carrier which I think was down to a lack of viscosity.

Your box will run on needle rollers so this shouldn't be a problem but the old boxes are metal to metal and need viscosity in my opinion.

Of course my box might have gone wrong with the previous oil but my gut feeling was an oil problem.

Regards
Steve

[rgh0]

Hi Paul,

I did try Redline last year but my once good original Lotus Cortina gearbox only last about 10 minutes of qualifying before 1st gear welded its self to the carrier which I think was down to a lack of viscosity........

Steve

The viscosity of Redline synthetic is the same as any other oil with the same viscosity spec so I dont understand the comment. I presume you used the correct viscosity oil for the box in which case it cant have been viscosity?

The advantage of Redline and other polyol Ester synthetic base stocks is that it retains its viscosity specification better with temperature variation and with use compared to conventional mineral oils and poly alpha olefin synthetic oils. Lots of other advantages in results in all the other various types of lubrication and wear tests

I had an interesting gear failure at a manufacturing plant I recently started managing that wrecked a $50k gear transmission. I discovered the oil suppliers sales person and the equipment manufacturer ( both large multinational companies) or our in house maintenance people had not recognised that they should not use EP gear oils ( typically GL-5 rating these days) with high levels of phosphorous antiwear additives in a steel worm and brass gearwheel combination as the phosphorous attacks the brass. It took at lot of digging with the oil companies engineers to get them to admit they had supplied the wrong oil for the application.

Using a GL-5 oil in a dog box is an option as long as the box does not have any brass components, otherwise stick to GL-4 oils that have low levels of sulfur and / or phosphorous and are safe for use with yellow metals.

cheers
Rohan

[patrics]

Hi,
The Redline oil I used was MTL 75W80 API GL-4 gear oil that says it satisfies the gear oil viscosity requirements of 75W, 80W
But I think it pours more easily than other gear oils of the same weight? so not sure about the claim of viscosity.
Now my gearbox failed because the oil carburised between 1st gear and the carrier and I couldn't separate them with a 20 ton press.
For the last few years I have used Valvoline fully synthetic oil without issue and I change the oil and 10 minutes later my ?1000 gearbox is toast - I can't afford not to learn from my mistakes!

Of course I could be wrong and the box could have failed anyway.

When I went to the UK importer for Redline they were a bit reluctant to recommend an oil for an old design gearbox but I was confident it would be okay after reading so much on the Internet.

Anyway if asked for advise I will only recommend based on personal experiences.

Regards
Steve

[fattogatto]

I don't think you can do better than Mobil 1 90w Synthetic.

[rgh0]

Hi,
The Redline oil I used was MTL 75W80 API GL-4 gear oil that says it satisfies the gear oil viscosity requirements of 75W, 80W
But I think it pours more easily than other gear oils of the same weight? so not sure about the claim of viscosity.
Now my gearbox failed because the oil carburised between 1st gear and the carrier and I couldn't separate them with a 20 ton press.
For the last few years I have used Valvoline fully synthetic oil without issue and I change the oil and 10 minutes later my ?1000 gearbox is toast - I can't afford not to learn from my mistakes!

Of course I could be wrong and the box could have failed anyway.

When I went to the UK importer for Redline they were a bit reluctant to recommend an oil for an old design gearbox but I was confident it would be okay after reading so much on the Internet.

Anyway if asked for advise I will only recommend based on personal experiences.

Regards
Steve

Yes you used the correct gear oil for your box

Yes Redline may "appear" to have a different flow rate when pouring it out of a bottle and appear "thinner" but that is very different from the viscosity tests done for an oil. The Redline oil was the correct viscosity for your gear box and would have retained it properties under more testing conditions and for longer than alternate mineral oil base stock gear oils

Redline polyol ester oils have far greater oxidation resistance than any other oil type so if you burnt up this oil you would have burnt up any oil. Why your first gear seized on the shaft is an interesting question but it is highly unlikely it was due to an oil change and 10 minutes running unless there was previous damage given the experience others including myself have had with Redline gear oils for many years in the same gearboxes in similar situations. Was the gear a Quaiffe needle roller or a brass sleeve set up ? If brass sleeve the likely cause was the previous use of a GL-5 style EP gear oil with high phosphorous or sulfur levels causing corrosion and laying down of corrosion products which are a similar dark colour. If it was a seized needle roller I would need to see the damage to understand the failure mode and the possible lubrication contribution.

My understanding is that most Valvoline "full synthetic oils" are not true synthetic but "severely cracked" mineral oils. Calling these oils "full synthetic" was allowed following a court case in the US where companies such as Valvoline claimed they were not "natural mineral oils" due to the heavy processing, despite them starting as natural mineral oils and thus could be called "synthetic". They are good oils and I use some of them as their price performance ratio is good but their molecular structure is not a true synthetic structure like Mobil 1 poly alpha olefin base stock or Redline polyol ester base stock .

As a side comment US courts also accepted arguments in a different case that heavily modified sugar molecules to make them lower in calories could be called "natural" rather than "artificial" because they started as natural sugar molecules. It just goes to show that you not ask lawyers to make chemical engineering decisions


A multinational oil company very like the Valvoline one you are using recommended the wrong lube oil for the transmission that recently failed and cost the company I recently started working for $50k for a rebuild for the second time in 12 months so you cant take any sales person recommendations / comments on face value. You need to be an educated purchaser and know what you are buying and why when it comes to engineering technical components such as lube oils.

Personal experience is always the most valid starting point and when you add to it the needed engineering analysis you can understand what is going on and why. The web is full of contradictory personal experiences understanding why the differences is what adds information to the data.

cheers
Rohan

[fattogatto]

Just to stir the pot a bit . . . .

Here is a statement (warts and all) quoted from a very well-respected race engineer/racer in the US regarding Redline Oils.

"my results , however were derived in three ways... the hundreds of gboxes and motors from all forms of racing that passed thru my hands during my career from outside sources , the other probably hundred long term clients that I ran for years and years that I could actually track the wear, and the formal engineering study of oils in general I did on my own dyno over the course of seven some odd days on three different motors for about 60 hours... and the results were crystal clear and absolutely unambiguous...

every single solitary oil out performed the redline from a wear stand point. the bores in the motors were worse by far and the ring life was bad enough to require rebuilds far sooner than all the others. gearboxes would come in that the cheapest guys on the planet had run off the shelf 90 wt in for 5 years and the ring and pinions and bearings would look brand new. redline gearboxes would come in with a season or two on on them and the bearings would look like they had been lubricated with water and the ring and pinions the same. there was no discernable difference between any of the other oils made by anybody else. only the "redline " clients were so noticeably worse than anyone one else. if it had been the case of redline being just the same as everyone else or within the hysteresis of the data I would have said " well... who cares " but that was not the case."

I would point out these data points are from racing gearboxes (Hewland Mk 9 and FT-200 for the most part). That said, I would always defer to the factory/builder recommendations.

[rgh0]

Yes like I say
Lots of opinions not much engineering analysis is what characterizes the internet. Sorry I tried to add some information to the opinions and observation and why they may or may not be observed

race engineer? - you mean mechanic? But if this expert who has observed hundreds of engines and gearboxes understands lubrication failure modes and wants to come and discuss them I am happy to talk about it.

Happy to talk about lubrication with anyone but as I think I said recently in a post. I only now debate pros and cons of various lubrication systems now with real lubrication engineers and half of them don't know what they are talking about either.

By the way the people who build aircraft gas turbines that keep you reliably in the air, use polyol ester oil base stocks due to their lubrication properties and heat resistance.

cheers
Rohan

[patrics]

Hello Rohan

I must admit I have limited knowledge on the measurement of viscosity but at the time our gearboxes were developed it amounted to something like letting a quantity of oil at a known temperature run through a tube of a set length / diameter and measuring the time taken.
If the modern method for measuring viscosity differs from that and allows for a thinner oil to be labelled as the same viscosity then I am more convinced that the oil was at fault in my gearbox.

You are obviously well aware that our original gearboxes run steel on steel so I would imagine that they rely heavily on the actual thickness of the oil to keep the surfaces apart whereas a modern gearbox has proper bearings so not so important and a thick oil would probably just make the gearbox run hotter.

I still wonder why the Redline importers were so reluctant to recommend an oil for my old type gearbox.

Anyway I'm not a lubrication engineer so feel free not to discuss it any more.

Regards
Steve

[Chancer]

There would only be relative movement between that gear and the mainshaft when another gear was engaged, i.e. it would not have been taking any drive and would just have been freely rotating at a different RPM to the mainshaft, the differential revs would have been the highest on the first gear hub.

Nonetheless I am very surprised that it seized, I am wondering if the tol?rances or surface finishes were correct and/or it had the correct o?l grooves machined, I confess that I cannot recall how the standard set up is, someone mentioned bronze bushes, I dont recall them and think it was just two ground surfaces and a helical o?l groove.

If designed and machined correctly to the correct tol?rances that is to say the OE ones it should not require anything special in the way of lubrication, pretty much anything even old and contaminated should suffice, there are much more critical and borderline lubrication areas in a gearbox, it does sound like the change of o?l provoked the failure but I think there was an underlying cause which you wont be able to find if the parts are welded together.

I had an Escort with a noisy gearbox, I had to pass it on to a girlfriend after wrecking her car (long story) I said that i wanted to top up the o?l that weekend, oh no dont worry she said I got the guys at work to do it, i should explain that this girl was a serial liar, it got noisier and noisier and whenever I wanted to look at it she kept claiming she had had it topped up (she must have been worried that I would take the car back) eventually it ground to a halt and I changed the box, the one I removed had never had any o?l in it ,between myself and the person who I bought it from who never touched the gearbox it probably ran for 5-10000 miles without any lubrication which shows you how robust and tolerant the standard Ford gearbox is, OK it wasnt raced and was only coping with a stock 1300 engine but it didnt fail from a gear seizing on the mainshaft but through bearing failure..

[rgh0]

Hi Steve

I am always happy to discuss. I just reserve actual "debating" for lubrication engineers with whom I have had many disagreements with over the years So I tend at times to get over enthusiastic on the topic for which I apologise. (read my posts for oil versus grease in trunnions and ZDDP in engine oils if you dont know what I mean )

The apparent thinness of synthetic oils at room temperature reflects their tendency to not thicken at reducing temperatures as much a mineral oils due to their different molecular structure. Thus their apparent low viscosity when poured from a bottle at room temperature, this apparent low viscosity has very little to do with how they actually perform at normal operating temperatures. Viscosity is typically rated for oils at 100 degrees C and the winter viscosity rating ( with the W after it) measured at low temperatures around and below 0 degrees C. depending on the actual rating. The ranges of viscosity allowed by the SAE rating scale are also substantial and can lead to significant differences between similarly rated oils or similarities between differently rated oils. Actual operating temperatures of lubricants are also much higher within the bearing and between the gear teeth than in the bulk lubricant in the sump or gear box so rating a lubricant at 100C can also be misleading it the temperatures is subtantially higher at the point of actual lubrication.
The following articles give some more information

http://www.upmpg.com/tech_articles/motoroil_viscosity/
http://www.machinerylubrication.com/Read/926/gear-oils

The other compounding factor is that lube oils are not perfect Newtonian fluids especially, as they age in service and their viscosity can vary with shear rate.

http://www.machinerylubrication.com/Rea ... -viscosity


Additive packages are just as critical as the lubricant base stock and these are even harder to understand as most manufacturers only talk about them in broad terms given that the details tend to a a commercial secret

http://www.machinerylubrication.com/Rea ... ation-role

All of this makes selection of oils a challenging proposition for professionals let alone the average user of an old Lotus seeking information on what modern lubricants to use. Many oil company sales people have no idea about the issues and basic principles and if your application is not in their book which only goes back maybe 20 years they will either guess or be reluctant to give you an answer.

The fact that modern oils of any type are infinitely superior to the oils in use when the Elan was first made 50 plus years ago is indisputable. The challenge is in selecting the right modern oil for your use and application in your old Elan given the complex range of factors involved. Even people with the huge resources and technical knowledge of the major oil companies and car companies get it wrong sometimes - e.g. the issues with the mayonnaise like sludge buildup in engines running modern synthetic oils with certain types of premium unleaded fuel in cars did that did not get hot enough for long enough to vaporise the blow-by contaminants from the engine oil.

cheers
Rohan

[Chancer]

Rohan, I always enjoy reading your postings on lubricants, it broadens my knowledge, some things I can clearly relate to yet did not know the technical reason. I read with interest the comments on the zinc additives, could you put up a link please to the thread on o?l vs grease for the trunnions?

On my Caterham I machined the uprights to accept the rose jointed lower wishbones, not having dust covers like trunnions they dont last as long as lubricated trunnions, the machined upright retaining the grease/o?l drilling in the centre is not as strong as the correct later uprights.

[rgh0]

here is one discussion in the forums about oil versus grease that has some good information

lotus-elan-f19/maintenance-t20905.html

there are a number of others if you google search

I apologise for the thread drift

cheers
Rohan

[SJ Lambert]

Hi Rohan - do you reckon that this Penrite PRO GEAR 75W/90 would be a good second choice behind Red Line Light Shockproof Gear Oil (blue) for my Mk V Hewland box?
Cheers
James

[rgh0]

I dont see any reason why it would not be suitable. It is fully synthetic from Group 4 and 5 base stocks so will have good temperature resistance and of the recommended viscosity for a Hewland Mk5 with your sort of engine and car.

cheers
Rohan