semi synthetic to synthetic

[leemanuel]

HI,

i know the last oil change on my car used semi synthetic oil, car is a 2001 done 55k, am i ok to change back to fully synthetic for the next change? or do i need to stick with semi??

what i mean is will changing back to syntehtic cause me any problems??

Lee

 

[Beetnik]

The general rule is it's OK to go mineral > semi synthetic > full synthetic but not the other way.

So I'd be going back to fully synthetic and staying there.

 

[sweeper]

The general rule is it's OK to go mineral > semi synthetic > full synthetic but not the other way.

So I'd be going back to fully synthetic and staying there.

Where does it say that? It makes no difference, personaly i don't see the advantage of fully synthetic oils in road cars, unless you drive very very hard for long periods, where a standard motor oil might break down. i use a cheapish (if bought at trade) semi and change every 6 months (7-8000miles) as i don't really go a bundle on the longer intervals, especially on higher mileage cars, but each to their own i just happen to believe that a reasonable quality oil, with regular changes is better than an oil that is over-spec'd for the job and left in for a longer time.
Going back to the original question, why would it not be ok to change back from a synthetic to a standard or semi? i will refrain from using the word mineral to describe a standard oil as semi and fully synthetic oils are in fact mineral oils that are basicly taken apart and rebuilt, so they are not man manufactured oils as the name would suggest.

 

[leemanuel]

that was kinda my thoughs too - wqas going to use a quality semi synthetoc and as i do minimal mileage (6k max a year!!) then just cjange it every 6 months?

what do other users do or use???

 

[mikevernon]

At the risk of stirring up some controversy, I would say that the choice of oil is irrelevant for the majority of owners who will only keep the car for a maximum of 3 years or 40,000 miles. They certainly wouldn't notice any real difference between the most expensive fully synthetic and Tesco Value Oil, and would probably even get away with not changing the oil at all!
Having said that, there can be no doubt that using a modern, low viscosity fully synthetic oil will greatly extend the life of an engine as well as significantly improving the fuel consumption.
Personally I bought a lifetime supply of Shell Helix Ultra Diesel 5W40 Fully Synthetic because it is absolutely top quality oil and because it came at a very good price. I use it in all my cars, petrol as well as diesel. I have now sold off most of the surplus but if anybody else on here wants any, I have a little left at £3 per litre (which compares rather well with the £14 per litre charged by Shell garages and Mercedes dealers!).

Please email me direct at [email protected] if interested.

 

[Will]

Mike's offer sounds generous and good value, failing that if you know someone who has a costco membership, you can buy Mobil 1 0W-40 fully synthetic oil for £19.99+ vat per 4 litres. Can't be bothered with lower grade (mineral/semi-synth) oils at that sort of money, personally.

Will

 

[leemanuel]

thanks all - been to costco today and got mobil synthetic and done the change - also put a new thernostatt on the 330ci .

all around good day

cheers for the help