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Discussion Starter #1
Years of fooling about and trying pretty much EVERYTHING thats on the market

Endless discussions as far as what oil I should use, in which case.

You will hear thousands of different opinions regarding which oil is best, statistics which mean nothing really, tests that all companies make showing that their oil is THE BEST and so on....

In the years of my experience and personal testing though, THIS will be my bible from now on, and I'll be sticking to it.

Today I will let you know of my findings regarding GEAR OIL and I will share with you my personal views on the subject.
You can take my advice if you like :)

so,

GEAR OIL:

Most people think that the A and Z with oils, is to be as thin as possible and not breaking up under high temps, in order to have the less friction, but at the same time stick to the metal parts in order to keep them lubricated.
In short, this would be ideal, and this is what I thought as well, but never been able to know if what I was using would provide me with such results.

In theory, oil is oil, even if you use engine oil in your gearbox, it will still lubricate it, it wont go black, it wont overheat in normal driving conditions etc, but this is just HALF of the story.
But do you just want to lubricate your gearbox, so it wont seize ? or do you want to protect it ?

Oil can not only break its velocity under heat, it can also break under pressure !
So, a gearbox needs a HIGH PRESSURE OIL in order to cope under the extreme conditions of a gearbox (torque converter).
These oils are either branded with EP (extreme pressure) or GL (as in GL3, 4 and 5)
Grades 4 and 5 of pressure, (more pressure) are used in gearboxes with LSD, which obviously stresses out the gearbox more and produces more pressure.

Now,
oil companies, in order to achieve these extreme pressure withstanding conditions, add microscopic parcels of metal in their formula.

You will hear LOTS of people saying that you shouldn't use GL5 oil in your classic car's transmission.
This is true, but why ?
Because the formula which contains the microscopic parcels of metal (GL4, GL5), will also have a CHEMICAL reaction with your old gearboxes bronze parts (synchro's) and destroy them.

HOWEVER !!!

There are GL5 formulated oils that are NON METALLIC !!!
Which is what I used and tested in my Sprint for many years, and had NEVER EVER had any problems with crunching 2nd gear or noisy diff or breaking a diff- which are all common problems with the boxer family gearboxes.

CONCLUSION:

Regardless of the MAKE of the OIL that you use in your gearbox from 1970's till today, make sure that you use a NON METALLIC FORMULA OF THE GL5 or if you cant find a GL5 which is non metallic, go to less pressures like GL4 or GL3 , again non metallic.
I was told that the GL5 might stiffen up my gear changes a lot, but I used it anyway, and it had no effect on my gears.

The grade of the oil I'm using is 80W90, which is the ideal grade.
For EXTREMELY freezing temps , you can use 75W90, but you wont need it, even in UK.

GRADE:

Although its a bit hard to explain grades, I'll give it a shot :
The higher the gap between the grades (5w50, 10w60, 75w140 etc) the more you can "strech" the oil before it brakes up.
Think of a bubble gum, if you take it and stretch it, the 10w60 buble gum will stretch to , lets say, 10 cm , while the 80w90 bubble gum will stretch up to 3 cm before they snap.

Again, IN THEORY, motor oil companies have formulated these high velocity grades to keep the breaking "lines" as big as possible.
However ! When those lines DO BREAK, which oil will give you the biggest gap of unlubricated parts ?
You guessed it, its the 10w60.

So , the shorter the gap between the weight and grade, the less possibilities you have of damaging something when the oil breaks.


NOTE:

If even now, you believe that you want to put normal 20w50 engine oil in your old transmission, please note that you should get a NON FOAM formula of the 20w50 oil, as normal oil usually foams up after stirred up by the diff and gears, and that will cause you a big problem (apart from the noise of the diff which you will also inherit).


So, again , gear oil : 80w90 - Non Metallic Formula GL5

Engine oil is a different story, so will get on that later :)
 
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you anus!






















ha ha!! only joking mate.


very informative, I think i'll read it a couple of times to digest the details.

so is there a magic brand you have been using Chris?
 

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Doh!, I just changed my box and put 75w90 semi synthetic, If only you posted this 2 days ago lol :)
 

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Interesting Chris... I like to go with Miller's where possible, I've checked with their boys in the lab and recently purchased the following...

Millers ... ...

CFS 10W60 ENGINE OIL TRIPLE ESTER
MOTORSPORT CRX LS 75W90 NT GEARBOX OIL

And a litre of their 300 RACING BRAKE FLUID :)

I'd be interested in your thoughts :)
 

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Discussion Starter #5
I'm not familiar with Millers mate, I'll need to search for their product specs to see if they mention anything regarding the oxidation of the bronze parts of the gearbox.
Best way is to contact the manufacturer directly as these questions are too technical even for the salesmen and dealerships (most of them dont know what they are on about).

What surprises me is that most of the guys in UK use 75w90 in your gearboxes.
That type can go all the way down to -40 degrees ! You dont live in Siberia ! hahaha

In any case, if you insist in going with 75, I found the Red Line 75w90 NS to have good specs, so I would use that:
Red Line Synthetic Oil - Gear Oil for Manual Transmissions - 75W90 NS GL-5 Gear Oil

Personally, I use KENDALL oil. I did rather not mention it as I dont want to be advertising and branding, but since you asked .... :)
So why risk that extra 5w for temps I dont really need ?
If its -35 Degrees outside, I wouldnt even go to pee, let alone go for a drive ! haha

80w90 goes down to about -25 Degrees - Which in my opinion is MORE THAN ENOUGH !
Plus you dont get that big a gap if or when the oil brakes up ;)

Rodg, I'll get back to you regarding the engine oil you use.
Have to look it up a bit.

And just to make something clear, I havent become THE OIL EXPERT all of a sudden :tut:
I just FINALLY know what to look for and where ;)
 

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GRADE:

Although its a bit hard to explain grades, I'll give it a shot :
The higher the gap between the grades (5w50, 10w60, 75w140 etc) the more you can "strech" the oil before it brakes up.
Think of a bubble gum, if you take it and stretch it, the 10w60 buble gum will stretch to , lets say, 10 cm , while the 80w90 bubble gum will stretch up to 3 cm before they snap.

Again, IN THEORY, motor oil companies have formulated these high velocity grades to keep the breaking "lines" as big as possible.
However ! When those lines DO BREAK, which oil will give you the biggest gap of unlubricated parts ?
You guessed it, its the 10w60.

So , the shorter the gap between the weight and grade, the less possibilities you have of damaging something when the oil breaks.
Yep the 10w60 oils tend to shear faster than the other grades. Bigger the gap but some are better than others.
But look at the HTHS index also.
a 50 may give you the same oil pressure as some 60's out there.
HTHS of 300v 15w50 is the same (~5.3) as Castrol TWS 10w60 so will most likely give you the same oil pressure under load(real conditions). But the VI of 10w60 is high (175 or something) so is thinner on start up (at normal temps 10-30c- not talking about sub zero here) and lubricates faster.

:thumbs:
I like oil topics:)
 

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She's about to get new AGIP 10w60 (the engine runs smoother now on this stuff i am sure) and I will lube the box up with the 80w90 suggested :thumbs:.

I'm thinking about a sandwich plate on the filter for an oil temp gauge/ one day an oil cooler. Do any of you run these on your road car? The oil cooler could be helpful in summer but i doubt temps are a problem now.

Cheers
 

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Soody, your Sprint looks like it has an oil pressure gauge (sender). Correct?
I've fitted one to my 33 (from an older 33 1.5QV) and I can use it to roughly judge oil temperature (cold, hot, too hot). It tells me that my oil only gets too hot on the track, not in the traffic. So the standard car doesn't seem to need an oil cooler for normal use, and I'd be concerned that adding one might delay or stop your oil getting up to temperature?
 

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Discussion Starter #9
Well look,

as far as engine oil, basically the same principle stands as the gear oil, with the difference that it should be more carefully selected as IMO engine parts (bearings) are more fragile and need better lubrication.

So basically, by using multi viscosity oil (10w60 for example), you get 10weight when car is cold (about -25 Celsius) and 60 weight when hot.

For very cold climates, freezing, I would use 5w30, because its thin enough to get you started in the morning, and it heats up quickly, reaching 30 weight when warm.
Now, if its not that cold, and you do push the engine to high revs all the times, I would use 10w40, which can give you more dens when hot before breaking up.

For track days or REALLY HOT climate, theoretically you SHOULD use 10w60, BUT,

by doing this you increase the risk of not lubricating the engine parts when the oil shears as Brit said.

Now these numbers are clearly relevant to climate conditions, driving style and manufacturer recommendations, so its really hard to pick the right one.
For example, Alfa Romeo JTS engines recommend exclusively 10w60 Fully Synthetic oil. (not that you can get a 60 thats not fully synthetic....)

What happens is that to achieve these high range gaps, oil companies formulate additives to keep the oil's chemical structure solid, so this comes down to how much you trust the brand of your oil.

Personally, I have tried 2 types of 10w60 in my 33 on high temps and on the track.
First it was the SELENIA RACING 10w60, which came out of the engine after 4000 khms feeling more like just fluid rather than oil.
Then I tried the EXTRON 10w60 which was a direct manufacturing and bottling in Germany (by the way keep in mind that most countries bottle up their own highly known brand oil), and that not only became sludgy, it also smelled very bad and got black - burnt ! - it lost its viscosity.

Then I moved to 10w40, and to my surprise , even after a track day on a hot day, the oil is still oil coloured, and still feels like proper oil !


Whats important to know is this:
After the old single viscosity oils, oil companies have developed formula's to achieve this range / gap in viscosity and temperature ranges.
I found that a gap of 30 grades is the most effective and reliable.
Anything beyond that is achieved by lots and lots of additives, so at the end of the day, you end up paying big money for a high range 10w60 oil, which has more additives than oil in it.

Our engines need oil/lubrication.

So my advice is, if you'd like to give it a shot yourself, get a good 10w40 Semi Synthetic oil and try it !
It definately WONT damage your engine, so nothing to worry about there.
I think you will be amazed ;)
 
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"Personally, I have tried 2 types of 10w60 in my 33 on high temps and on the track.
First it was the SELENIA RACING 10w60, which came out of the engine after 4000 khms feeling more like just fluid rather than oil.
Then I tried the EXTRON 10w60 which was a direct manufacturing and bottling in Germany (by the way keep in mind that most countries bottle up their own highly known brand oil), and that not only became sludgy, it also smelled very bad and got black - burnt ! - it lost its viscosity.

Then I moved to 10w40, and to my surprise , even after a track day on a hot day, the oil is still oil coloured, and still feels like proper oil !


Whats important to know is this:
After the old single viscosity oils, oil companies have developed formula's to achieve this range / gap in viscosity and temperature ranges.
I found that a gap of 30 grade is the most effective and reliable.
Anything beyond that is achieved by lots and lots of additives, so at the end of the day, you end up paying big money for a high range 10w60 oil, which has more additives than oil in it.

Our engines need oil/lubrication.

So my advice is, if you'd like to give it a shot yourself, get a good 10w40 Semi Synthetic oil and try it !
It definately WONT damage your engine, so nothing to worry about there.
I think you will be amazed ;)"




two points here though Chris, firstly, there should be a point made that ALL synthetic or blended oils have "suspension additives" and these are supposed to hold the dirt the engine creates, so that an oil drain removes the filth along with the oil itself,

so a black oil on the way out is actually helping keeping your engine clean internally.

a crystal clean oil 5000 clicks old, might not be!




and finally, after this have been debated over and over again, another one agrees with my advice from the start,

for a road/modified engine, a good semi synth 10/40 will perform very well indeed.

I have used this and nothing else in everything I have owned in last three decades, including some very highly tuned, stressed and revving race bike engines (16k rpm!)


IMO (again!) there is no need for liquid gold under most circumstances, simply get a decent 10/40 and change it often, none of this "oil lasts for 30,000 miles rubbish!"




full race engines should be approached very differently, the temps are less of a concern as the cars tend to be better prepared with regards to engine temp stability anyway, but the stresses certainly, and for this reason, there will be people who can justify the liquid gold's out there.

Tom, BLS, if I recall correctly uses the Miller 10/60 in the race 33, but not the nanodrive version with miniature robots buffing your crank and blowing kisses at your pistons!!!!

ha ha!!


branded 10/40 all the way for me, Motul, Silkolene, and a little known surprise in the recipe, Eneos Oils, have all performed faultlessly for me over the years, including the bike, race, jap turbo modified engines, etc etc etc


shrew



Phew! I'm wearing this box out!
 
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PS - the gearbox GL5 thing is excellent work Chris,

who'd have thought all this time that the oils used over the years in our little willy wonka box of cogs could have actually been weakening the synchro's!


potentially has a LOT to answer for eh?



was there a brand of GL5 you found to be good enough to recommend Chris?
 

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Discussion Starter #12
Shrew, I'm glad we agree :)

Just to clarify something regarding the black oil - I do agree that oil going out black means that its working, but mine wasnt just black. It smelled very intense and it became sludgy, as if it was in the engine for a million miles !

Also, just to clarify something else, I also change the oil frequently, around every 4000 khms.


In my gearbox, I used the Kendall Three Star, as mentioned before, and when I opened up my gearbox to change some leaking seals, it was as good as new inside. Never ever had issues with the gears either.
Its probably the best gearbox I've got.

Engine wise, I've also went for Kendall in my Sprint this time,
it's the Liquid Titanium 10w40.
I havent fired that engine up yet, but its close to been.

In my 33, I'm currently using GULF Tec Plus 10w40 and I'm very happy with it, but I'll be switching to Kendall in that one as well after a couple more oil changes. (Trying to get rid of the old 10w60 residues first).

Same Gulf 10w40 is used in my 156, and I'm delighted to report that it has stopped consuming oil as much as it used to !


This is some info regarding the Kendall GT1 Liquid Titanium :

Features & Benefits

-Exclusive Liquid Titanium additive technology for extra protection against engine wear
-Formulated for engines equipped with turbochargers or superchargers
-Excellent resistance to viscosity and thermal breakdown at high temperatures
-Protects against sludge and varnish formation
-Protects against rust and bearing corrosion
-Highly resistant to foaming
-High ZDDP content for additional wear protection for engines with flat-tappet camshafts (SAE 20W-50)
-Racetrack-proven performance
-GT-1 High Performance with Liquid Titanium meets or exceeds the requirements of: API Service SN (except SAE 50)
 

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Hi Chris

Great article on gear oil. Thanks

I was wondering what to change it too.

Never heard of Kendall though!
 

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I tried 300v 20w60 once (my engine likes the 60 grades) and thinking the gap was only '40' so maybe more stable than the 10w60.
But when I changed the oil it came out thick and like black treacle also. It wasn't hot though.
It has a HTHS of around 7.2!!
but just too thick on start up also.

After 4000 kms I've been using the Castrol TWS 10w60 - no complaints so far. lower OP than the Motul 20w60 (HTHS of 5.3) but still within limits when pushing it hard.
But prices are just too high now and it only comes in 1 litre bottles.

Going back to 300v 15w50 me thinks. Got 4 litres stored away.
Add a little zddpmax also to bump up the zddp level.
 

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10-40 for me and as shrewbeee said ! change it Regularly !
I think my OP at hot idle would be too low with a 10-40

I get about 0.7 bar at hot idle with a 15w50 (Motul) or 10w60(Castrol). But a good 4 bar at 5000 rpm

I'd be scared putting in anything thinner for the idle pressure.
 

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There's your problem! Idling ! You should be bouncing off the rev limiter not driving like a girl, now go and stand in the corner:lol:

:lol:

wish I could mate. town driving here is a nightmare, lights every 10 metres!

but seriously a 10-40 would be too thin I'm sure for some boxers. you don't want less than 0.7 bar at idle.
 
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