Which Oil should I use?

[cjm911]

I have recently bought a second-hand 993 and now wish to add a little oil, but can't be certain what is already being used and I don't want to mix it. I therefore want to replace the lot...but with what? Yes, Mobil 1 is the recommended choice and is about £50 for 10 Litres, but there are now semi-synthetic oils that are, allegedly, just as good. Whilst these are of course far cheaper (about £15 I think), I wonder if a) they are in fact just (or nearly) as good, and b) it is false economy, if you then change it more freqently because you can afford to.

Does anybody have a view on this issue or is it a no-brainer?

Merry Christmas

Colin

[sportsandclassic]

Mobil 1 oil which grade is £50 for 10 litres ?

Thanks

mike

[kiko]

No oil is too good specially on an engine that relies on it to cool! Even if it costed £50 the liter I'd use nothing but the best.

[996tt_stevo]

Speak to "oilman"

He advises best oils and takes into consideration of age, mileage and driving.

He can also be contacted here www.opieoils.co.uk/

[cjm911]

Thanks for your comments...I take your point and will err on safety, as it were!

[Globulator]

Semi synth is a bit better than regular oil being a cracked version. Full oap synthetic is however miles ahead in terms of stability and slipperyness.

Full synthetic has an instrinsic sae rating, which is why 0w-40 is easy for it, but impossible for regular oil. Interestingly to make regular oil 10w-40 you start with 10sae and add polymers. Heat and age then turn this back into thin sae10, varnish, plastic and sludge.

Another interesting factoid is that sae40 is a measure of viscosity, in a warm engine 0w-40 is the same thickness as 10w-40 despite people thinking that somehow synth is thinner. It merely starts off nearer the target viscosity when cold, saving fuel and wear.

Oilman will sort you out!

p.s. My first post on Opera on the Nintendo DS lite

[stuttgartmetal]

Drain the tank and let it drip dry.
Mobil One from costco, yep.

[truckpdt]

Well there is one school of thought that I read recently in a magazine article that says you should attempt to find out what the car has been run on to date (before you purchased it) before using Mobile 1 or a fully synthetic oil. Apparently the use if such an oil has such a strong cleaning mechanism that it can remove any sludge that was previously coated to the various mechanical parts and then cause blockages else-where. Obviously this is just what I read.

I have a 993 and Northway recommend Texaco Havoline...which is a semi. I also know that fully synthetic oils are used in engines with precise tolerances....now the 993 may fall into that bracket, it's not that old, but for example I know that my old TVR Griffith would simply leak if you used a fully synthetic oil, but then again that entire engine is based on an old Land Rover block anyway.

Also remember that the most expensive is NOT necessarily the best for YOUR car.

I'd be interested to phone around some of the specialists and ask them....Northway, Ninemeister, Intaporshe, Strasse, Autowerke, Autofarm, JZ Machtec etc. Get some sort of combined view on the subject for a 993.

[Globulator]

truckpdt said:

Well there is one school of thought that I read recently in a magazine article that says you should attempt to find out what the car has been run on to date (before you purchased it) before using Mobile 1 or a fully synthetic oil. Apparently the use if such an oil has such a strong cleaning mechanism that it can remove any sludge that was previously coated to the various mechanical parts and then cause blockages else-where. Obviously this is just what I read.

This is only a potential problem if you stick an (hugely expensive) ester based synthetic into a car that has been poorly maintained. PAO synthetics like Mobil 1 in a reasonably oil maintained engine should not be a problem.

Magazine articles are written by people like you and me, expert status is definitely not guaranteed, a fact I was reminded of reading the EVO100 question about running in (p37). Ignoring all of the testing and measured and photographic evidence of people like motoman the guy basically says: 'Well the manufacturer must know best', probably without even reading what they said. He also explained the plain bearings needed running in to remove the rough spots, and that the honing patterns only job was to retain oil: two clear signs of total ignorance!!

truckpdt said:

I have a 993 and Northway recommend Texaco Havoline...which is a semi. I also know that fully synthetic oils are used in engines with precise tolerances....now the 993 may fall into that bracket, it's not that old, but for example I know that my old TVR Griffith would simply leak if you used a fully synthetic oil, but then again that entire engine is based on an old Land Rover block anyway.

What testing did you do to establish this? One thing that will happen is that the synthetic is nearer it's target viscosity when cold, when a dinosaur oil will be very thick;- so if you had a leak it may have looked worse when sat on the drive.

truckpdt said:

Also remember that the most expensive is NOT necessarily the best for YOUR car.

I'd be interested to phone around some of the specialists and ask them....Northway, Ninemeister, Intaporshe, Strasse, Autowerke, Autofarm, JZ Machtec etc. Get some sort of combined view on the subject for a 993.

Good idea. JZM put Castrol fully synthetic in my 930 without prompting, to be honest whatever engine I had synthetic is sooo much more stable, much higher shear strength and far better at lubricating from cold and at extreme heat that I'd not look at anything else for a car I valued now. The protection is simply massively better.

[nel]

I'd suggest that you don't go thinner than 5W-40 on a 993, or the engine will start finding new leaks that it didn't know it had. I use that grade of Mobil 1, though some talk of 15W-50 (a grade of Mobil 1 that I've never seen in the shops).

Personally I reckon topping up with a good synthetic can not be a bad thing, irrespective of what oil is already in the engine. However, if you have any doubts then the complete oil change is the obvious way to go.

[silver993tt]

nel said:

I'd suggest that you don't go thinner than 5W-40 on a 993, or the engine will start finding new leaks that it didn't know it had. I use that grade of Mobil 1, though some talk of 15W-50 (a grade of Mobil 1 that I've never seen in the shops).

Personally I reckon topping up with a good synthetic can not be a bad thing, irrespective of what oil is already in the engine. However, if you have any doubts then the complete oil change is the obvious way to go.

I've had Mobil 1 Motorsport 15W-50 in my car before. Now it has Castrol synthetic 10W-60.