synthetic or semi synthetic oil

I've just seen advert for oil plus oil filter change at National Tyres garages for £20. Is this any good please? Thanks.

Fully synthetic always. (Except for air cooled engines).

I would prefer the cheapest genuine fully sythetic oil to the best semi synthetic. Most brands are just fine. I've used everything from Halfords to Mobil 1 and loads in between.

Christian.

National can be good. I would just insist on seeing the oil that's going in and actually see them put it in. Then again, they could put any old rubbish in a can! Do you not know anyone who could do this for you if you can't do it yourself?

IMHO, if you do nothing else at all to your cars engine, an oil and filter change is something that should never be missed or skimped on. Buy fully synth for a modern engine. It's a few quid more but could save a bundle in the future.

How about Tesco's own brand oil (not Value!)? I've used their oil the last time I changed the oil - I checked the actual specifications of the oil and they matched what the manufacturer required (also matched Castrol oil too!).

If the manufacturer suggests, for example - 10W40 Semi Synth - what would you suggest putting in - it seems the fully synth stuff is more like 5W40. Any issues with using that? Also, are there any issues with mixing semi and fully synth oils?

Thanks

D

As long as it meets the minimum API standards suitable for the engine as stipulated in the operators book then any oil will do. You will usually find that Toyota actually recommend conventional oil as being just as good as synthetic for their engines. Every Toyota of that age that I have owned certainly hinted that synthetic was a waste of money at that time. Brand is totally unimportant and a brand is the result of marketing success. I have never known any problem with any oil meeting the relevant manufacturer and International standards appropriate to an application. It is not rocket science because it tells you what you need in the book, more than likely under the bonnet somewhere, and certainly on the oil can. The other variable is the oil viscosity but anything from 5w/30 to 15w/40 will be good in the UK for your engine.

Huw

That's all that is important. If the value oil also meets the manufacturers quality standard in terms of API rating then you need nothing more.

If you read the text of your book you will probably find that Toyota specifically mention that mineral oil is all you need.

what

Don't mix oils except for topping up. You can use most common fully synthetics if you feel the need. Beware that there is the possibility of using an oil too good for your vehicle. Some of the more expensive specialist oils for very extended drain intervals are just not suitable for your engine and could be worse for your engine than using the Tesco Value oil [assuming it meets the standards needed]. I notice that the Rav averages less than 3000 miles per annum. At that mileage you will just waste your money on synthetic oil because you should change your oil every year, eighteen months max, regardless of mileage covered in that time.

Huw Huw

If it's fully synthetic, then I'd use it.

5W40 may work better than 10W40.

Yes. Don't mix any oils if you can help it, whatever type they are. Top up with the same type as you used at the oil change, if you can.

Christian.

I used National Tyres in Leeds recently for an oil change, knowledgeable and friendly chap, happy to talk about the work done, the oil used was Castrol Magnatec IIRC.

Magnatec is a semi-synthetic, IIRC. One of the better ones, though.

Christian.

I asked them about an oil change for my old SD1 3500. Seems they have a 3 litre limit on their advertised offers. The SD1 takes about 5.5 litres. My

2.8 BMW 6.5 litres. ;-) They quoted 45 quid, which is far more than DIY - and they didn't have the filter in stock.

Kwikfit in Balham did it for 25 quid - Mobile 1 semi-synthetic. Near enough the cost of DIY - without all the hassle of doing it on the road and disposing of the old oil, since I've got no garage or driveway.

BMW now recommend every two years if the service indicator doesn't say earlier. That's with their fully synthetic.

Thanks to everyone who replied to my original question. You have all been very helpful.

I'm not the OP, for me the car is a 1998/S Pug 306 - but I'll bear that information in mind. Thanks. David

My mum's new Vauxhall Astra 1.9CDTi/120 is 30,000 miles or 2 years. It was one of the selling points, given that Volvo were charging her over 500 quid every 9000 for her old V40.

Christian.

Let's not confuse the issue talking about different vehicles that have computer monitored flexible service intervals using specialised lubricants. They are even particular about the performance grade of synthetic used.

Fact is, Toyota Rav4 does not need synthetic and synthetic will give no measurable benefit in that car. If in doubt the owner should read the manual as this takes precedence over Usenet.

Huw

I can't see how a hydraulically cooled internal combustion engine would not benefit from fully synthetic oil. It is simply better. Mineral/semi might be OK, but synthetic will be better.

Christian.

In what way relevant to the Rav4? In particular, will the engine last longer? I say no.

Huw

I say yes.

It has better lubrication qualities. It has better life qualities. The engine will wear more slowly, and hence will last longer.

Christian.

Only if the wear due to the oil film not being good enough is comparable to the other causes of failure.