Oil filter change in old car - how often?

[Doctor Drivel]

Says on the can 100% Synthetic

"SAE 5W/40 API SM/CF

ACEA A3, B3, B4."

On the API, S mean spark ignition engine, C means Compression Ignition (Diesel) The next letter is the level of protection, M is the highest for spank ignition, hence SM. Only fully synthetics reach SM. M was introduced about 4 years ago. You may see many SL oils around. That is very good, but M is meeting the most stringent of specifications.

SAE 5W/40 means the viscosity.

Note: API have introduced a SN about a year ago. I am unaware of any market making oil to this level yet. It takes time for makers to get their oils made, tested and approved by API and onto the market.

[The Other Mike]

Then, by definition you are a badly educated idiot.

There is no point in mentioning them now, it would only confuse you further.

[Davey]

Read that again. The use of 'spank' and 'SM' in the same sentence must be a coincidence, right?

[Doctor Drivel]

If you say so - yerrr. Duh!

[The Other Mike]

That is a common prceedure on cutting tools to establish 'zero' height above the material you are machining.

Ditto

[Doctor Drivel]

Do you meant the oil wasn't still like brand new? Wow!

[The Other Mike]

No I didn't. Go back and read what I wrote.

[Doctor Drivel]

I did. You were shocked it wasn't brand new!

[thirty-six]

So you don't examine your oil, that's fine by me.

[thirty-six]

Garages will top up via the vent plug so overfilling the box. Can't remember the details, but the oil wont work as required when the box is overfilled like this. It's better to have low oil than an overfilled box. Next time I'll be using a molybdenum disulphide loaded oil, probably a Rocol product. There's no need just now, needs a few years (probably 4) and miles before the standard gearbox oil starts showing effects of deterioration. The extreme pressure additive in a standard gear oil is not particularly hard wearing.

[thirty-six]

[Doctor Drivel]

[Doctor Drivel]

Just found out that API have round symbol that means if it is on the can, it was tested by them and meets the spec. Most do not get the oil tested by API saying their oil meets the API spec. It cost $300,000 to test one car and the oil, and more $$ for subsequent tests. Only the real big companies can afford that. Small companies may never recoup the testing costs.

[Doctor Drivel]

Actually since about 2004 Mobil 1 is no longer a true fully synthetic. Mobil lost a test case against Castrol re Magnatec which was claimed to be fully synthetic when it was in fact a hydrocracked Group IV mineral oil. The use of hydrocracking paraffin etc into engine oil makes a boost to profit from utilisation of lower grade stocks. As a result Mobil themselves moved to it, so basically synthetic can mean "true" polyolefin etc or blend of cracked mineral oils.

There is a true synthetic still available - Miller, however I think it is about £65-69 for 4L.

[Dave Plowman (News)]

If it started without choke on a cold day that simply means the mixture is too rich. So it would used more petrol than it should, wear out the bores quicker, and produce excess emissions. probably down on power too - if the carb was otherwise correct.

[Another John]

I say, Dr.! Is that really you? Haven't seen you here for yonks and yonks! Dare I say "welcome back"?

J.

[thirty-six]

[Doctor Drivel]

As fitted to the Marina, Maestro and Metro, the main service interval (with 1980's oils) was 12,000 miles without any intermediary interval.

They might survive, but their economy and performance will suffer, along with driver satisfaction.

[Doctor Drivel]

With "pure" synthetic oils the oil is very fluid at those temperatures. This reduces drag on start up and gets oil to the bearings ASAP, reducing wear. It also gives starter motors longer life as they do not need to work so hard. If "pure" synthetic oils are used as standard, then the starter can be smaller. This is less drag on the battery giving longer battery life as well. More economical as less energy is taken from the crank to recharge the battery - better mpg. Knock on is that a smaller alternator, battery and starter can be fitted saving cost and weight and giving better mpg.

I can only think of using:

1. "pure" synthetic oils
2. Suitable tyres
3. Using the "advanced" type of petrols.

[Doctor Drivel]

Too right. Gearbox oil is often left. It needs changing in an economy car probably sometime within six months to get rid of all the swarf from manufacturing and allow for initial wear-in of the cogs, and thereafter at every 20,000 to 40,000 miles unless driven particularly sedately.