View Full Version : Cars - and oil change intervals.

18th Aug 2008, 15:32
I don't normally drive through Arizona dust and I was looking for some practical information on oil changes/mileage and came across THIS (http://neptune.spacebears.com/cars/stories/mobil1.html). It's convinced me, as I use Mobil 1 anyway, that 20,000 miles between changes is the way to go, rather than as low as 8,000 miles on a BMW oil change indicator - at 80+ for the oil + bits.

What got me thinking was a friend's brand new Porsche Cayman - 20,000 miles before the first service! Then again, I got 240,000 miles out of 3 Series by using el-cheapo oil. So maybe any oil would 'really' do 20,000 in the UK.

18th Aug 2008, 15:41
I never used to 'change' the oil in my Jaguar 3.4 Mk II, as it consumed oil so fast that it needed topping up after 200 miles to stop the oil pressure warning lamp from illuminating.
In those days (late 60s) you could buy a gallon of Duckhams Q20/50 quite cheaply, and I always carried a can in the boot.

Loose rivets
18th Aug 2008, 16:54
Ha! So that was you that bought the last can of Duckhams just before me!! Your 3.4 was parked just beside mine.

What was it? a pound and sixpence if I remember correctly.

I think 20,000 miles is a route to...well, a mucky engine at least. Oil is the life-blood of the engine, don't get mean with it. (especially with big old American loose pistons.)

GM stuff in the states puts the warning light on at about 3k if you are doing half city and half highway. It does not seem to have a 'semi synthetic' setting.

Mind you, and oil change and filter at Oilcan Harry's using Penzoil can be as little as $20

The Mercedes uses Mobil I - but here in the UK I see that as a 0 - 40 oil. What sort of viscosity is 0 ?!!! the Mobile 10 -40 is half the price. !!

I haven't had to buy any oil for the MB yet cos servicing came free with that model. Next change I'm in for a shock I expect, though I have found a dealership that will let me do it and put it onto the main records. Time will tell.

The trouble with these cheap places is the grease monkeys that use power tools to do up drain plugs. They came very close to wrecking my sump on a Caddy NorthStar engine. I used about 120 f/ lbs to undo it. The car would have been a write off if the casting had broken.

My fear was not in vain. I have my SonIL's little BMW while I'm home, and while I was trying to get it all up to date for him I found that the sump was cracked where the plug goes in. It was dripping a cupfull a week. I found that undoing it closed the crack, so I drilled the nut head and wire-locked it aircraft style. (I do that with all my cars now.) cos a typical plug torque is 15 f/lbs

18th Aug 2008, 18:29
What was it? a pound and sixpence if I remember correctly.Or one pound exactly from Halfords in four 2 pint cans, including a filter. Usually packaged in a large 'Duckhams' paper bag.

18th Aug 2008, 18:31
20,000 miles between service/oil change is not unusual these days.

Five years ago I bought an Octavia vRS, and was offered the options of 10k or 20k service intervals. Done, apparently, by using slightly different synthetic oils, amongst other things. As I was doing some long distance commuting at the time I opted for the 20k interval. A couple of years later when I was posted closer to home the dealer changed to the 10k interval at my request, no problem.

Mind you, older, classic cars require different treatment. On my classic Minis I used full mineral oil for the first 500 miles whilst running in, and then changed to semi-synthetic, with 3000 mile interval, after that. This is mainly due to the fact that the oil has to deal with the engine, gearbox, and differential all at the same time.

Impress to inflate
18th Aug 2008, 23:18
I may be wrong here (I've been wrong once before) but as oil gets older, it picks up more "cr^p" from the combustion process and becomes more acidic thus helping to wear out the engine faster. If I am wrong on this mater, please let me know would you.

P.S Big fan of Mobil 1, used it for years.

19th Aug 2008, 00:58
My eldest son, who is a true race car expert, as an owner and driver, insists that we change oil and oil filters in everything we own ever 3,000 miles or three months. Transmission fluid every 6,000 miles. In his race cars he changes oil every race. But then again, in his race cars and trucks his engines are producing nearly twice the horsepower that they were designed for.

(Yes, he goes through a lot of engines.)

19th Aug 2008, 07:24
Con will you save me a barrel or two of that oil?
Iwill arrange shipping.:ok:

19th Aug 2008, 09:32
Agreed con-pilot race engines need frequent changs . A friend races clasic Kawasakis and changes oil after every meeting . He hasnt had a DNF so far this season !

So far no one has mentioned diesel engines . They have a reputation for mucking up oil much faster than petrol engines but with frequent changes just keep running .

Finally I use Mobil 1 in a 1972 Lotus But I change it every year or so despite the mileage being low .

19th Aug 2008, 10:30
Some diesel engined vehicles monitor the oil quality and adjust the service interval accordingly. Over the past five years mine has averaged an oil change every 16,000 miles, which is about my annual total. The oil required (VAG spec 507 00) is not so readily available as some other premium brands, but similar in price to a quality synthetic.

19th Aug 2008, 10:59
Being in the industry as an absolut minimum I would recommend an oil and filter change every year irrespective of mileage.

If you do predominately long journeys at relatively high speeds the need to change the oil is reduced because the engine and it's components are operating at their optimum temperature so combustion product blowby is minimal, this is what destroys the oils ability to lubricate. For someone who does mainly short journeys at low speeds it may well be advisable to change the oil & filters every 3000 miles despite what your service book may say.

Modern oils are technically very different to good old Duckhams, which I spent a lot of money (relatively) on in my youth, most are synthetic based and retain thier lubricity for longer under more arduous conditions than a straight mineral oil can hope to do. Also modern engines run tighter clearances and higher loads on bearings so the oil quality really is critical.

Don't skimp on oil cheap is not necessarily cheap in the long term even at 80 for an oil and filter change it is a lot cheaper than an engine re-build!


Loose rivets
19th Aug 2008, 12:52
Transmission fluid every 6,000 miles.

The pundits on the Cadillac forum warn agains using the vacuum machine on an oil change. The danger of stirring up metal in the pan is very real, and of course auto-boxes are very critical. Remove the pan and clean the screens every change.

I learned this just after having mine done. Again the f:mad:wit that did it messed up. Left the filler cap just sitting on top of the casting. Seeing it in daylight...350 miles away, for the first time. Cap and dip-stick still there. Phew!

So, what is the difference between Mobil I in America and the UK. Totally confused I is.

Windy Militant
19th Aug 2008, 13:17
Don' t forget the air filter! I once bought a MK2 Escort Estate nice body work but a bit down on power. No problem I had a 1600cc Cortina engine in my old rusty MK 1. Discovered the reason for the power loss, young me laddio who sold it to me had hoicked out the air filter to increase the performance. Not a good plan when you live next to a sand and gravel works. The sump was full of aluminium paste which used to be the pistons. :ugh: