Run the car until the oil thermostat opens. This can be determined by confirming that the front right wing is warm to the touch or the oil temperature gauge has dropped from the second mark on the dial. Then leave to idle for a minute or two on level ground.

This gives sufficient time for the scavenge pump in the engine to return surplus oil to the tank and will allow the oil level gauge to settle. With the engine still idling, withdraw the dipstick, clean it and re-insert it for a few seconds. Withdraw it again and read the oil level. It should ideally be between the high and low markers in the twisted section of the dipstick. You should now also confirm the indication on the oil level gauge.

If the gauge indication concurs with the dipstick reading you can rely on the gauge at any convenient stop to check the oil level.

Approximately 9.5 litres for a normal oil and filter change. The system holds in total about 11.5 litres but it's not always possible to fully drain the oil cooler and it's associated pipework.

All normally aspirated 964s use a dual spark plug system with dual distributors. The secondary distributor is driven via a rubber belt which can be deteriorated by ozone build-up within the distributor (caused by the sparking) if not vented. The venting kit (p/n 000.043.202.52) only costs around £10 and is very easy to fit.

Although the belt itself is not designed by the factory as a serviceable part - the official line is to replace the distrubutor assembly complete - it IS possible to replace just the belt although it does require some disassembly of the distributor involving the drilling out of a pin which locates the drive gear.

The belt is available from many independent parts suppliers but NOT from Official Porsche Centres.

Surprisingly, the pin (p/n 930.602.922.00) and the sealing O-ring (p/n 911.602.102.01) are available from OPCs.

Drilling holes approx 1.5" in diameter in the outside face of the airbox creates a significant increase in the induction noise, particularly when accelerating.

It's unlikely it allows the engine to produce any more power - but it sounds as though it does!!

Certainly. Both of these re-useable filters use a cotton-type material instead of paper and rely on being impregnated with a special filter oil once cleaned. They can be re-used time and again provided they ar eproperly cleaned at the recommended service intervals.

Over-oiling should be avoided as the surplus oil can be responsible for contaminating the air flow meter in the induction tract and this can be one reason why some people would prefer not to use them.

Top end rebuilds can only really be justified if cylinder compression is poor, evidenced by bad leakdown numbers.

Compressed fuel charge leaking through badly sealed valve seats or stem seals or past the piston through worn or broken piston rings are the common causes of poor leakdown performance.

Leakdown numbers can be the best clue to the condition of an engine. Typically 10 to 15% could be considered normal and 20 to 25% is bordering on the need for a top end rebuild. Much over 30% is considered a good candidate for top end work to improve valve and piston ring seals although engines will still operate well with leakage exceeding these figures albeit with some loss of efficiency (and power).

Oil leaks can often add justification for a rebuild but rarely should they be the prime mover for such action.

A G-Pipe is a bent tube whose shape roughly resembles the letter "G" which is used to bypass the final (or secondary) silencer. It allows for the final silencer to be removed saving approx. 12 kilos of weight and resulting in a more "raspy" exhaust note.

The Cup Pipe is a much straighter pipe used to bypass the primary silencer which fits across the back of the car. So called because of it's use in the Cup races, the Cup Pipe save approx 11 kilos of weight but has a little more effect at reducing the exhaust back pressure than the G-Pipe and helps release a little more power.

The resultant sound of the Cup Pipe is a little quieter than that with a G-Pipe.

You can reset the variable parts of the DME's program by discomnnecting the battery for 5 - 10 minutes. It's then advisable to let the engine idle for 5 minutes before taking the car for a "spirited" drive for 20 minutes to allow the DME to re-learn your driving style.

A contaminated Idle Stabilisation Valve (ISV), vacuum hose loose/missing, possible oil overfill, or dipstick not fitted correctly.

There is also a TSB on the subject of a modification to the wiring entering the air flow meter. This modification prevents the wiring contacting the ventilation hose and thereby causing an electrical instability. TSB 9005 (here) refers.

This raises it's head now and again, it is thought the undertray can keep heat in the engine and cause premature exhaust valve guide wear, though this has not been proven conclusively, the undertray does provide a smooth under surface for aerodynamic benefits and it is often cited as a need to pass EU drive by noise regs.

This is commonly a symptom of a failed DME relay. Replacing the relay will often solve the problem. The original DME relay fitted to the 964 was a 944 part number and constant use gives rise to corroded contacts and failed coils. The new relay has the part number 993 615 227 00 and is located in the fuse box that is on the right side of the front luggage compartment