OLD oil (20 years)!!

vikingaero

It's perfect for topping up hire cars!

AdrianHi

vaio wrote: »

Synthetic oils - Lubricants whose base stocks are pure chemicals. They are not based on the simple refining of crude oil but are manufactured by the conversion of certain chemicals into synthetic bases with controlled structure and predictable properties.

Not sure how to interpret this in the context of other definitions I've read.
"not based on the simple refining of crude oil", yes, OK with that.
"base stocks are pure chemicals", could be an acceptable definition if you accept the "pure chemicals" were obtained as a result of processing refined oil in this so called synthesis process. At the end of that process the resulting chemicals molecular structure is quite different from refined crude oil, but did start out from refined crude oil.

LandyAndy

I have a 25 litre drum of 20W/50 that I liberated from a fork truck company that was closing down some years ago. Ideal for my Landy whose engine is essentially a 1940's design. As others have said, not for a modern engine, though.

AirCooledHeaven

New_Dude wrote: »

Any oil experts here? I have a big barrel (plastic type) Quantum diesel oil, bought from VW dealers, from 1990....just found it in the back of shed during a clear-up. Is this still useable after so many years? Or has it gone "off"?

Your 1990 oil will be absolutely fine. As long as you're putting it in a 1990 car. Modern engines require all the additives developed during the 18 years your drum has been in the shed...

vaio

AdrianHi wrote: »

Not sure how to interpret this in the context of other definitions I've read.
"not based on the simple refining of crude oil", yes, OK with that.
"base stocks are pure chemicals", could be an acceptable definition if you accept the "pure chemicals" were obtained as a result of processing refined oil in this so called synthesis process. At the end of that process the resulting chemicals molecular structure is quite different from refined crude oil, but did start out from refined crude oil.

I can see your argument because “cat cracking” and other fiddling can produce some weird and wonderful compounds out of normal crude. Wikipedia comes up with this……..

“Hydrocracked/Hydroisomerized = API Group III base oils. Chevron, Shell, and other petrochemical companies developed processes involving catalytic conversion of feed stocks under pressure in the presence of hydrogen into high quality mineral lubricating oil. In 2005 production of GTL (Gas-to-liquid) Group III base stocks began. Even though they are considered a synthetic product they are still mineral base stocks and counted as the mineral part of all semi-synthetic lubricants. Group III base stocks [with certain amount of mixture of PAOs and esters and Group V] are considered synthetic motor oil ONLY in the United States.I][URL="http://en.wikipedia.org/wiki/Wikipedia:Citation_needed"]citation needed[/URL][/I Group III based lubricants are not allowed to be marketed as "synthetic" in any market outside of the USA.”

Which the way I read it says that if it started out as oil then no mater how much clever fiddling you do it still can’t be called synthetic (unless bizarrely you sell it to the Americans), the best you can get is semi-synthetic

AdrianHi

vaio,
If I re-read the text I have carefully enough and compared with yours they seem to agree. The so called synthetic (and not just semi-synthetic) oil commoly used still has it's roots at the oil refinary with "true fully synthetic" oils being rare and expensive. See what you make of it, interesting bit in bold.

oilman wrote:

3) What are the differences, in layman's terms, between mineral, semi-synthetic and fully-synthetic engine oil? (In terms of structure and performance.)

Before we get into details, the first thing to realise that there is no chalk and cheese difference between mineral and synthetic based oils. After all, the chemical compounds which make mineral engine oils so much better are themselves synthetic.
Synthetic lubricant bases are stepwise improvements on mineral oil, with more desirable properties and fewer
undesirable ones. The second important point is that there's no one thing called 'synthetic'! There are several different types of synthetic lubricant, and to say something like: 'the Supergrunt GTI TURBO must have a
full synthetic' is meaningless unless the 'expert' explains what sort of synthetic he means.
Equally, to imply that dreadful things will happen if the 1970 RV8 is run on anything other than good ole mineral oil is ridiculous. It may not need a 2007 synthetic, but it isn't going to come to any harm if the owner uses a 2007
synthetic!
The most basic type of synthetic is really a special mineral oil. Known as 'hydrocracked' bases, these are made in oil refineries by putting certain types of mineral fraction through special processing, so they cost more than the usual mineral types but not much more. They are useful because they resist evaporation at high temperatures. Although
used for years for genuine technical reasons, they are now popular with marketing men because the magic sexy word 'synthetic' can legitimately be printed on the label without spending much on the oil inside the can!
Yes, all low-cost 'synthetics' contain anything from a few percent to 20 percent (i.e. 'semi-synthetic') of special mineral oil. Using fairly simple chemical compounds or gases from oil refineries or other sources, it is possible to 'synthesise' or build up tailor-made lubricant molecules which have very desirable characteristics, such as great resistance to cold, heat, evaporation losses or excessive thinning as they get hot. These are the true synthetics, and the two that are used in engine oils are PAOs (poly alpha olefins) and esters.
Neither is cheap! PAOs are related to mineral oils, and are the ideal carriers for all the chemical compounds used in mineral oils. Because they do not gel at very low temperatures, all genuine 0W-something oils have to be based
on PAOs to pass the 0W test at a sub-arctic -35C.
Esters were originally made for jet engine lubricants, and to this day all jet oils are ester-based. Although similar in performance to PAOs, they have a valuable extra trick: they are good lubricants and help to protect metal surfaces. Esters help with transmission and valve train lubrication. 100% fully synthetic oils are actually quite rare, probably because they are very expensive to make, and even more expensive to buy.
Even so, an ester/PAO with a very shear stable multigrade polymer is the ultimate oil for high output engines that are worked hard, which means racing.