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Old 10-20-2008, 09:40 AM
desertdriver desertdriver is offline
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Location: gilbert az
 
Join Date: Mar 2007
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Mein Auto: 335i sedan, sport paddles
Quote:
Originally Posted by 335i Driver View Post
1. Your statement that all synthetic oils are hydrocarbons is absolutely false. Many of the best synthetics are esters, diesters and polyesters, therefore they have oxygen atoms in the molecular chain, thus by definition they cannot be hydrocarbons.

2. The study you posted is about gear lubrication at high temps, not even a valid comparison to engine lubrication at low temps. Note the lowest temp tested was 50C or 122F. While I agree that there may be times that a mineral oil may be better than a synthetic the question is much more complex than that. There are many variables including the type of synthetic.

However, why don't you ask your engine if it is starting at 20 below zero if it would prefer a solid mineral oil frozen at the bottom of the crankcase performing no lubrication at all or a synthetic that is liquid and is actually being pumped throughout the engine and to the top of the cams. My friends that is where 80% of the wear on an engine takes place and where mineral oils fail severely compared to a good synthetic.

1) You apparently dont know the use of the word "absolute", check your facts. Mobil 1 is a polyalphaolefin, eg a "hydrocarbon" that is not fully saturated, and its just about the best performing synthetic out there because it isnt blended as much with mineral oil base stocks. Lesser, cheaper synthetics are made from alcoholic esters in a polymerization reaction and heavily blended with minearal oil basestocks, this is a cost control measure, over synthetics based on PAO of contolled polydispersity that are used in the better synthetics like mobil 1. Oh, by the way esters are hydrocarbons technically, oxygenated hydrocarbons to be precise. A pure oxygenated hydrocarbon oil would be very expensive as they are derived from vegetable oils. So in the end the esters or polyesters that are in synthetic oils are heavily blended with mineral oil components anyway.

2) On the low temp comment, what do you think startup is for the first 10 mins. No one ever said that synthetics dont do better up at high temps, they do and that is why BMW uses them. Not so some idiot nimrod can run his car hard just after startup.

3) Anyone who is starting their engine at 20 below zero, should get an engine block heater, put the car in the garage to keep it warm, or else suffer the damages. Yes the damages will be less with a mobil 1 type oil, but there will still be accelerated wear vs using an engine block heater.

To get back to the real subject here, synthetics do not alleviate concerns about running a car hard before warmup. Like I said before anyone who thinks they can ignore the BMW engineering recommendations is a arse, and I would never buy a car from them.


Anyone who is really interested here is an article on them:

http://www.viragotech.com/fixit/AllAboutOil.html

all oils have temperature dependent viscosity, eg, viscosity index. Mobil 1 is one of the best, and is a synthetic hydrocarbon. Its all about the oil polydispersity, not whether its a hydrocarbon or an ester.

Last edited by desertdriver; 10-20-2008 at 02:49 PM.
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