Firstly, for your info and for anyone else reading this in the future, lets get one thing straight that so many people get wrong.
Oil pressure has nothing to do with low oil levels.
The only time oil pressure can be affected by low oil level is when there is virtually no oil left in the engine and the oil pick up pipe will then start to suck up air instead of oil. Not many of us let the oil level get that low !!
Oil pressure is simply a product of the oil pump sucking up oil and pumping it round the bearings in the engine. These bearings are a very close fit, so the oil cannot "pour" out of them, but seeps out, and the pump is trying to send it round faster than it can escape, hence the "pressure".
Now imagine instead of the oil pick up pipe sucking oil from the bottom of the engine ( the sump ) it is sucking it from a pint glass full of oil, and returning it to the pint glass after it has gone round the engine. Here we would only have a pint of oil, but as long as the pick up pipe remained submersed in the oil, we would have good oil pressure
I hope that made sense !!!
Regarding low oil pressure.
Those bearings, the main ones being the "big end" bearings at the crankshaft end of the pistons "connecting rods", and the "main bearings" that the crankshaft is supported by, in the main engine casings, wear away as the engine gets older.
When this happens the oil, instead of seeping from them, starts to pour out faster. As the oil pump has a limited ability to keep up with this accelerated rate of oil flow, it "runs out of steam" and the result is low oil pressure.
This is worse when the oil is hot, as it is thinner and therefore flows out of the increased gaps in the worn bearings faster.
The cure.
If this is the cause of your low oil pressure the only thing to do is replace the bearings. Unfortunately it is often not that simple as the metal on the crankshaft will often hasve worn away too. This then involves removing the crankshaft and having it re-conditioned ( "re-ground" as it is called ).
Also it is good practice to change the actual oil pump too.
All this is alot of work involving a complete strip down of the engine, and it costs ALOT !!
Sadly when an engine has got to this condition there are almost certainly other partys that have worn out, such as cam bearings, piston and bores etc. Most folks don't bother trying to recoindition them, they have to buy a replacement engine.
On this subject one has to be very carefull as many non VAG reconditioned engines are sadly lacking in quality and one often hears tales of a locally sourced re-conned engine failing.
Generally it is wise to only buy genuine VAG engines and make sure they are serviced as per the instructions at the dealers to maintain the warranty.
Maybe others on here can recomend some decent non VAG engines, just for future reference ?
Here endeth todays lecture !!!!
