Thread: oil, filters and sh1tty nappies

Having watched JohnS (KhunMoo) do his 3.9 Isuzu filter change in his County last week, I can understand. It's a messy job as the filter is upside down and the oil goes everywhere unless one takes precautions.

Ron

Historically the oil filter was introduced long after the practice of regular oil changes, and as the filter remains effective (and may even become more effective) until it starts getting blocked sufficiently for the pressure relief bypass to open, there is no logical necessity for the element to be changed at every oil change - the oil is changed to get rid of what the filter is not removing (such as fuel dilution and fines below the filter size) and to replace oil which is becoming less effective than it was originally due to chemical breakdown.

When oil filters were first introduced, the filter change interval was usually at least twice that of the oil change. As the interval between oil changes has increased (mainly due to better oils!) there has been a tendency for the filter change interval to become the same as the oil change interval.

For example, just checking the owner's manuals - my Series 2a manual specifies oil at 5,000km and filter at 10,000km, but both the Series 3 and 110 manuals specify both oil and filter changes at 10,000km.

Note that all the manuals specify more frequent changes in severe conditions or on a time basis if used infrequently (usually six months).

As society has become more affluent it has become common practice to change filters at every oil change even if not specified by the manufacturer, and of course this is supported by those who sell them!

John

Originally Posted by p38arover

Having watched JohnS (Khumho) do his 3.9 Isuzu filter change in his County last week, I can understand. It's a messy job as the filter is upside down and the oil goes everywhere unless one takes precautions.

Ron

If it is like mine it has a drain plug underneath to let the oil out first - of course that doesn't get all of it.

John

Nissan specify the same change regime for the TD42T engine used in the Patrol, and probably for their other engines too.
What JD says is pretty much what I think too.

FWIW in a 300 Tdi, most of the oil that's in the oil cooler circuit remains when the oil is drained thanks to the routing of the cooler pipes. It just can't drain out, yet no one ever worries or about this, probably as they don't even realise it happens. (yes, I've gone to the trouble at times to undo the bottom union on the header tank and let it drain out. I'm so anal sometimes )
Another point with the Tdi is that when the oil cooler circuit opens, the oil by-passes the filter ! At least according to my reading of the oil circuit diagram.

Don't sweat it Dobbo. Normal service procedure.

Dobbo just service it according to your use and the manual and all will be fine. Oil's these days are good quality unless you are buying the realy cheap crap.

Originally Posted by JDNSW

If it is like mine it has a drain plug underneath to let the oil out first - of course that doesn't get all of it.

I think it did have - John drained it via a trough under the filter into a container on the ground.

I was parked beside him and I did my 300Tdi Disco at the same time and I slid a plastic bottle with the side cut-out up under the filter and unscrewed the filter into the container.

Neither car is driveway-friendly!

Ron

Originally Posted by JDNSW

When oil filters were first introduced, the filter change interval was usually at least twice that of the oil change. As the interval between oil changes has increased (mainly due to better oils!) there has been a tendency for the filter change interval to become the same as the oil change interval.

John

The first car I owned with a full flow filter had a recommended oil change interval of 1000 miles, and a filter change interval of 5000 miles. It also was supposed to be greased every 500 miles, at about twenty to thirty points from memory. Rear spring shackles and pins every 500 miles or weekly, whichever came first. Diff and gearbox oils to be changed at 10000 miles and 5000 miles respectively. The pre-war stuff I learned to drive on, and which was all a 1950's apprentice could afford, didn't have filters, with rare exceptions. The 1928 Dodge Six had something like a cloth sock in a canister (by-pass filter at that) which probably only intercepted the big bits. Air cleaners were primitive at best, and many had been removed and thrown away, as they needed to be removed and cleaned regularly on the dirt roads of the time.

You're showing your age there... A 1950's apprentice XD....poor thing. I do oil and filter changes ever 5000km. Mainly coz I can get both fairly cheaply, and well, if you're doing one you might as well stop being LAZY and do the other. But that's besides the point. In my head, the idea of doing the oil change then the oil & filter change is a bit like getting the air gun and blowing the stuff out of the air filter. The filter is not necessarily non-servicable after 5000km, it will still filter just fine...so if you're saving yourself $10 ever second service by not doing the filter all is forgiven. It's not a worry for me, the extra $ are worth the peace of mind.