5 Speed Box: Whirring in 5th after Redline oil change

[JonB]

And that?s another reason why I haven?t been in a rush to try a different oil - the recommendation of highly respected forum participants like Rohan who really uses his cars.

[The Veg]

Back when I had the Esprit I changed to MT90 in the gearbox (no idea what the PO put in before) and the improvement in shifting was quite noticeable. Good stuff.

[2cams70]

Regardless of whether Redline MTL actually is or is not a contributor to the noise you are experiencing deductive reasoning would suggest that the next logical step would be to change out the oil to see if there is any change in the character of the noise you experiencing. That would be the scientific approach not based on any opinions. You noticed the change in sound after having undertaken only two activities: 1) Changed the oil. 2) Changed the gearstick arrangement. You've already done a fair amount of work around 2). If it were me I would be doing a bit more work around 1) seeing that that possibility has not yet been eliminated.

Now for the opinion only bit. Redline may work fine in a transmission in good unworn condition but the same oil may not be so good in a transmission that has already seen considerable use. Redline may perform well under racing conditions but this does not necessarily translate that it performs well under real world driving conditions. Many, many issues often show up under real world driving conditions that don't show up on a dyno (OEM experience here!). Experience with one oil in one type of gearbox with one type of driver does not necessarily translate. A particular oil brand/type may perform well over "X" number of kilometers but without a standardised benchmark for comparison it's not really useful information because the standardised benchmark may have performed just as well if not better. Remember these gearboxes were designed well before high tech oils were ever developed. They may be able to utilise some of the advantages but then again they may not.

I note that Redline is not a supplier to any OEMs. Whilst that does not necessarily mean there's a problem at the same time it does not provide (for me at least) the same assurance as some other branded products.

[derek uk]

OEM's use a big brand name because they have done the tests to the required standard and can buy in quantity at a very reasonable price, i.e cheap. Companies like Redline also do the tests and their oil is just as good if not better. They can add some slightly more expensive additives and charge more. They wouldn't have capacity to supply the major motor manufacturers and they would also have to sell it to them at a loss.
Redline 10-50 High Performance Synth 5 US quarts/4.73L RRP ?85.38. OEM's might be willing to pay a quarter to a third of that. I say "might".

[JonB]

Naturally, a forum is going to present much opinion, and so I chose Redline based on a sort of general consensus.

@2cams70: Your point is clearly made and I do get it. As I said, I do intend to try a different oil when I next have it on stands. As I have just completed months of engine gearbox diff and propshaft work not to mention rewiring the nose cone with relays, engine bay refresh and fitting a new dashboard, I?m perhaps understandably reluctant to put the car back on stands just yet. That notwithstanding, do you have a recommendation for an alternative gear oil? A product made by Comma has been suggested so far.

[2cams70]

That notwithstanding, do you have a recommendation for an alternative gear oil? A product made by Comma has been suggested so far.

People must be having religious experiences with oils judging by the amount of passion that occurs whenever the subject is raised. Let's hope they are using the lubricants in their cars rather than for other unmentionable purposes!

My religion is an Australian brand called "Penrite". This is not because I have any evidence to support that they are the best but rather because I've been sucked in by their marketing, their prices are reasonable and I have not had any bad experiences with any of their products (the more I think about it the more it does sound like some kind of religion!!)

A very good economical product I've used in the past for manual transmissions is Castrol VMX80. It's a mineral product with exactly the same viscosity as that originally specified but with some extra additives to assist shift quality. I see Fuchs also offer quite a number of transmission fluids but I've not tried them myself. Fuchs are an OEM supplier to motor vehicle manufacturers but their products seem more tailored toward modern vehicles so I'm not sure how well they suit ancient vehicles. Syncho ring materials and design parameters have changed a lot in 50 years. My company used to use Castrol for OEM but has now changed to Fuchs.

The availability of a lot of the lubricants is region specific. I'm not sure where you are located and the availability may depend on this. I don't think it essential to use anything particularly high tech in a 50 year old transmission design for road use. ("high tech" being separate issues to "quality" and "meeting or exceeding the specification")

[rgh0]

I guess I have two religions when it comes to oil Penrite and Redline and one philosophy which is use the most suitable modern "real" synthetic oil you can find. A real synthetic oil is one made with group 4 or group 5 base stocks not group 3 ( as a result of a US court case) which can be claimed to be synthetic but is not really. Groups 1, 2 and 3 are just progressively more highly refined mineral oil it is only group 4 and 5 which are true synthetic oils. Most cheap "synthetic" oils are group 3 base stock

It used to be Mobil and Redline but in recent times as Penrite introduced more group 4 and group 5 synthetic oil based lubricants I have moved from Mobil to them for engine oils. Plus Penrite are a big historic racing sponsor in Australia so I like to support them when I can. I have stuck with the more expensive Redline products for diff and gearbox oils as these are changed much less often and I am looking for diffs and gear boxes to last for the life of my cars without major rebuilds if possible which is what Redline has given me so far over the last 30+ years and I dont think I will have time to carry out back to back tests with an alternative over the next 30+ years

For example the life of my Landcruiser front diff in mainly city use like mine is expected to be around 150000 kms due to wear on the spider gears.I am now at 430000 kms and counting while running it on Redline with twice the change interval as standard. The cost of the Redline gear oils may be twice as much but the group 5 polyolester base stock is much more heat resistant and lasts longer so I change at twice the normal interval so the oil cost is the same and wear performance better. Extending the life of gear oils is practical if the do not suffer deterioration due to heat like group 5 polyolester oils as the oil does not get contaminated with combustion products like engine oils do. Extended change intervals in engine oils due to the use of synthetics is not a good idea unless contamination levels are tightly controlled which is not possible in old carburettor cars but it is more possible in modern fuel injected close tolerance engines made these days which is why you see it more in new cars service intervals these days.

Forgot to mention the Golf R32 of my son and my Esprit that also have used Redline gear lubes for extended periods with improved gear changes and no other noise or problems

cheers
Rohan

[JonB]

Right - well it has arrived..

Comma 80W-90 GL4

13717.jpg (30.04 KiB) Viewed 2009 times

..so I'm ready to try a swap. I've done a quick viscosity test by putting a bit of Redline and a bit of Comma oil into separate cups, then turn them 90 degrees with the cups leaning at a 45 degree angle so the oil is in the corner. Very unscientific, but the Redline is as I suspected really really thin compared to the Comma oil at the same temperature.

So far so good. If my problem has its roots in low viscosity oil in a worn gearbox I may be onto something.

Full disclosure: I'm no oil engineer and nothing is being done in a scientific fashion. All results will be subjective impressions only! In other words I'd rather not have a "Redline vs. other oils" debate at this time. If it works for me, it works for me - YMMV.

[vxah]

So, how about warming the oils up to 50 degrees c or so and comparing viscosity then?

[rgh0]

So, how about warming the oils up to 50 degrees c or so and comparing viscosity then?

For multi grade gear oils the hot viscosity rating is done at 212 F / 100 C the cold viscosity rating ( the one with a W after it) is done at 0 F / -18 C. Also just comparing bulk flow characteristic in a cup or when you pour it with the viscosity measurement / rating which is measured when flowing under controlled conditions in a small tube can be very misleading.

At cold temperatures you generally want the oil to be as low a viscosity as possible to ensure adequate circulation while maintaining a sufficiently high viscosity at operating temperatures to also ensure adequate film strength and lubrication. This combination is more easily achieved over a long operating life using a synthetic group 4 or 5 base stock rather than a group 2 or group 3 mineral oil base stock with ground up polyethylene added ( yes that is what they use) as the viscosity index enhancer. The polyethylene molecules unwrap as they heat up reducing the viscosity reduction with temperature that mineral oils experience, however over time the polyethylene molecules get further ground up in the bearings and gears reducing their length and their effectiveness at controlling the viscosity reduction hence the shorter life of mineral gear oils compared to synthetics.

Note also a rating such as 75W says the oil at 0F has the same viscosity as a mono grade 75 rated oil (rated at 212F) has at 0F.

Whether a different style of oil will reduce noise in an old worn gearbox is worth experimenting with, but banana skins and sawdust will do the same apparently ( for a time )

cheers
Rohan

[2cams70]

Film strength is more critical than viscosity. Yes the two are related but a synthetic may have a different relationship film strength versus viscosity than a mineral oil so you may not be comparing "apples with apples". Comparing the viscosities may not mean much in other words.

[2cams70]

Whether a different style of oil will reduce noise in an old worn gearbox is worth experimenting with, but banana skins and sawdust will do the same apparently ( for a time

I don't really think that applies if he is going back to something more in keeping with the original OEM specification.

You don't actually need a multigrade oil in the transmission. That specification was never called for originally.

By the way I think John has also done more to the gearbox other than just change the oil and the shifter mechanism. I believe he's also had it apart to change the seals so a before and after test of a change in oil is still going to still be inconclusive because something else may not have been reassembled correctly or has changed. Is my understanding correct?

[JonB]

Full disclosure: I'm no oil engineer and nothing is being done in a scientific fashion. All results will be subjective impressions only! In other words I'd rather not have a "Redline vs. other oils" debate at this time. If it works for me, it works for me - YMMV.

Cough cough...

Yes, I considered the change in viscosity over a specified temperature range and (see above) acknowledged the empirical nature of my observations. There's really little point in debating what I might have done had I a) been bothered or b) had the time or c) had the equipment to do it scientifically. Is it not just quicker to swap the oil and simply try it out?

2cams70 is correct, I had pulled the gearbox apart slightly (and I documented that on another thread) but only slid the output shaft off its spline to renew the oil seal. In other words, none of the gearbox internals were disturbed.

Now I am waiting for an opportunity to do the deed... as there is much else going on in my house at the moment! At which time I look forward to reporting on the result.

Cheers guys!

[h20hamelan]

Film strength is more critical than viscosity. Yes the two are related but a synthetic may have a different relationship film strength versus viscosity than a mineral oil so you may not be comparing "apples with apples". Comparing the viscosities may not mean much in other words.

I dont have that many miles over 10 years on Ford OEM fluid

[JonB]

Well, I?ve done it, and the results are... disappointing.

Regarding the leaks, I think I overfilled the box with Redline. I read somewhere it was 2.1 litres capacity, whereas according to the manual it?s 1.7. This is not in the Technical Specifications section, it?s deep in the text of the 5 speed section. So fingers crossed that draining the MTL and refilling with 1.7 litres of Comma will cure the leak.

Sadly, it?s not cured the damned whirring noise. So I?m going to have to buy another gear stick with an intact anti sizzle bush.

While down there I had a look at the engine leaks. They?re on both sides of the engine, after I pulled it and renewed all the seals. I do not know what I did wrong, but I am mighty fed up with it.