hornchurchmale: depends what you compare with .nearly all oils are made to suit certain specifics . from mineral oils to fully synthetic. additives are added as per spec.
thus bit like comparing cars.. or books. all similar but some variations and often reflected in price! Castrol and Millers for example make a decent oil for classic cars.
hornchurchmale: so manufactures spend millions testing engines and components for best lubrication and you ignore? many oils are. very similar but will need to be different in different territories. Big difference using oils in hot desert regions all year versus artic conditions. The oil companies also go to great lengths testing own lubrication on different products all vying to be 'best' I would not presume to think one oil is best for all. eg racing.rally .sports cars . SUV. small sedans etc we are all welcome to sue whatever we want but if a product is under warranty.. using wrong 'non approved' products may invalidate it. many manufactures also give alternatives .. so you get a personal choice. end of the day its up to you.
jamesinfortworth: I proved to myself long ago that full synthetic oil is far superior to regular dino oil,, the savings on wear and tear plus added MPG far outweighs the slightly higher price of it I was shocked at the difference.
hornchurchmale: still important use correct oil example : historic /classic cars such as using rovers legendary V8 need 'classic' oil and using modern semi or fully synthetic oils actually causes wear on cams and other parts thus degrading engine! though one can of course use superior lubrication products these do have a cost. Oils are a specialised field and applications will vary . If one is OK with using an oil that is more costly with little or no benefits, then thats fine . For majority unaware of anything about oils or why different even such as 0-30w or 5-30W SAE etc and 2 stroke versus 4 stroke oils .petrol/diesel etc its more important to use designed oils suggested my manufacturer of your product rather than assuming we know better or are relying on 'advise' by others unless an expert in that area and product being used. These are few and far between. More often its comments and 'advise' given by somebody whom knows somebody who is claiming this or that etc . Bottom line simply put is the man in street is at less risk and better off overall following stated lubrication and intervals by the manufacturers in almost all cases.