A question I have often asked myself and this months EVO has finally answered the question
First of all mineral oil is made from crude oil. Synthetic oil is made from man made lubricants.
Which is better, mineral oil or synthetic oil?
Synthetic oil flows easier at low temperatures which is obviously good. Synthetic oil doesn’t burn as easily as mineral oil which make it good for performance engines. Synthetic oil is also more stable over a bigger range of temperatures than mineral oil
Why are synthetic oil becoming more popular?
Emissions regulations play a part. Because synthetic oils give less resistance emission are lower.
Is synthetic oil synthetic oil or are there different types?
All oil is made from “base stocks” and these come in 3 grades. Groups 1 & 2 are distilled crude oil. Group 3 is even purer than groups 1 & 2 but still comes from crude oil.
Groups 4 & 5 are man made chemical compounds.
What is engine oil made up from?
80-90% of engine oil comes from base stock. The rest is additives to enhance the oil, for example cleaning additives and additives which reduce acidity.
What are semi-synthetics?
They are not a 50% mix of base oils. Maximum semi synthetics are made from 30% synthetic base stock. The labeling is not the important thing with oils it is the oil specifications that should be looked at to see how good an oil is.
Mineral oils are sometimes recommended to run in an engine, why?
Synthetic engine oils can be too good are reducing friction which means things like the piston rings cannot bed into the cylinder wall. But every engine is different, it is best to go with what your engine builder recommends.
Can I run synthetic oils in an old engine?
It used to be that synthetic engine oils would leak out of older engines. Modern synthetic engine oils have largely overcome this with additives but as always better to go with what your engine builder recommends.
Can synthetic engines be recycled forever?
No, they degrade like any other engine oil
Interview with Brian Utton Castrol Automotive