Compression tester here, http://www.ebay.co.u...tester&_sacat=0
To test first have a fully charged battery, remove all spark plugs, screw in the compression tester into each cylinder in turn,
wedge or hold throttle plate fully open, and turn the engine over at least 6 revolutions, and the same for each cylinder, and note the readings,
I will have a look for the factory readings for you.
A compression test will not always reveal worn oil control rings, but a leak down test will give a much better view of what the problem is, but due to needing a compressor to conduct a leak down test, I would advise taking to a decent garage for this.
PS what oil grade are you using?
I'll give that a go when I can, I have bought a second car to keep the Z as a weekend car so it's no huge hassle anymore!
5W-30 straight from Nissan.
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