Opie oil man - supercharger oil Q

[cyberface]

This question's intended for Opie oil man - though anyone with the answer is welcome!!

I have a 1994 porsche 993, and run it on mobil 1 motorsport oil. The engine's done 74k miles so I tend to seek out the 15W/50 as it tends to consume the 0W/40 a bit more rapidly. Obviously an oil/air cooled engine needs oil that is good at high temps, when the 993 is stuck in traffic, the oil temp gets fairly high compared with your average water-cooled motor.

I have had a supercharger fitted, which is very cool - this is an Eaton M90 unit IIRC. The supercharger is sold as an oil-sealed unit, zero maintenance required. Is this likely? Presumably the supercharger has its own oil supply, it is possible that the oil would never need to be changed?

I've never heard of the superchargers blowing up due to oil problems, but I'd like some technical reason why - after all the internals are spinning at high speed under load.

[GreenV8S]

I've got an Eaton (M112) and it is sealed, but not sealed for life. I was advised to change the gearbox oil annually. I've got another eleven months to find out what oil it uses, but presumably it'll be a conventional gearbox oil of some sort.

[cyberface]

Isn't the M90 a newer design than the M112? The Eaton website claims the M90 is good for 150k miles without any maintenance. No mention of whether 'maintenance' means oil changes though.

[PJLarge]

I used to have a little M45 on my old old MX5. I can tell you that the oil in there is pretty damn smelly. Eaton USA state it is oil that's not easily available - IIRC it was only available to authorised supercharger service agents, the main one in the States being a company called Magnessun, although I have a contact that identified the oil and had a plentiful source. I'll send him an email later on if you like and try and get some.

Phil.

>> Edited by PJLarge on Saturday 5th February 21:48

[love machine]

IIRC, you are dealing with helical gears which have to take a fair bashing, hence I would have thought a Hypoid oil would be a good idea. However, I would do a google search for the right answer, it is out there. I have an M45 on my (real) mini and if I recall rightly, it should do 90000 miles on that oil. If it is correctly chosen, it should do it's duty as the gears aren't actually transmitting mega force. I would leave the bung in there as it may be hygroscopic (a bit).

I will log on later after I have perused my superchargers book.

[cyberface]

fair enough - if the oil's rated to last 90k miles then no worries!

The charger is currently supplying a max 6 psi IIRC so it's not exactly under huge stress.

[PJLarge]

I've checked with my mate, he doesn't have any of the oil left now

I did an oil change on my old blower, the oil is readily available in the States. One company that sells rebuild parts is ZZ Performance - www.zzperformance.com/zzp/products/products_eaton.htm

If you're going to pull the charger apart, there's no gasket between the mating surfaces that form the chamber the oil sits in, so you need some Loctite 510. I bought some especially for the job and have loads left. Next, whilst you're in there you may as well change the coupler. This tends to wear and makes the SC a little noisy with age. Again the website I pointed you to sells them.

Regards

Phil.

[opieoilman]

cyberface said:

This question's intended for Opie oil man - though anyone with the answer is welcome!! I have a 1994 porsche 993, and run it on mobil 1 motorsport oil. The engine's done 74k miles so I tend to seek out the 15W/50 as it tends to consume the 0W/40 a bit more rapidly. Obviously an oil/air cooled engine needs oil that is good at high temps, when the 993 is stuck in traffic, the oil temp gets fairly high compared with your average water-cooled motor. I have had a supercharger fitted, which is very cool - this is an Eaton M90 unit IIRC. The supercharger is sold as an oil-sealed unit, zero maintenance required. Is this likely? Presumably the supercharger has its own oil supply, it is possible that the oil would never need to be changed? I've never heard of the superchargers blowing up due to oil problems, but I'd like some technical reason why - after all the internals are spinning at high speed under load.

You are doing the right thing by moving a little thicker and the Mobil 1 would be a good choice, however with the higher temps it might be an idea to use an ester based oil, they originate from the jet engine industry and are well know for stability at high temps, I would look at the Silkolene Pro R 15w-50 which has been well proven in air cooled applications.

www.opieoils.co.uk/lubricants.htm

Mechanical constant-displacement superchargers go back a long way. (First used on GP FIATs, 1922-3). Bolt-on ones were popular 1930s to 1960s, then they faded out. Are they making a comeback? They are, (unlike turbochargers) easy to lubricate, because they don’t get very hot; the usual system is to use an oil bleed from the engine itself, so no special lubricant is needed. The vane-type variety (such as the 1950’s-60’s Shorrock s’charger) appreciate a spot of oil in the fuel; I usually recommend 1 or 2% 2-stroke oil.

However as to servicing the oil in the charger, I do not know, best to consult the manufacturer on that one.

Hope this helps.

Cheers

Guy.

>> Edited by opieoilman on Tuesday 8th February 11:42

[cyberface]

Thanks very much - will consider the Silkolene for next oil change