Paul B wrote:5000SE wrote:Paul B wrote: The engine oil pressure has nothing to do with the dipstick or whether it rises, but it might be a good idea to change it if it has sat festering for so long. Use a good 20/50, not some modern synthetic tosh.
If you're comparing a synthetic to a mineral oil of the same viscosity, the synthetic is better in every respect, and miles better in most respects.
Given a choice between a traditionalist view of sticking to mineral oil, and halving the wear in my engine, I'd go for the latter.
You can get 20/50 synthetic???
I'll buy some if you're selling it.
It will make sod all difference whether it's 5W/50, 10W/50, 15W/50 or 20W/50.
The first figure (W rating) specifies the oil's viscosity at zero degrees centigrade - so that's winter cold start thickness. The second figure is the oil's viscosity at 100 degrees centigrade.
So, unless you have a particulalry unusual engine which runs with a sump temperature of zero, I really wouldn't worry about the first figure (except that, at cold startup, a 10W/50 or 15W/50 will get oil up to your cam and rockers a lot qucker than a 20W could).
You'll generally not find 20W/50 synthetics because the flatter viscosity index of a synthetic nearly always gives you as much broader viscosity range. Just don't be misled by what the gradings mean.
The best synthetics on the market are the Mobil One range - Mobil pateneted its synthetic polymerisation process many years ago, so while most other so-called synthetics are hydrostabilised and hydro-cracked mineral oil which are legally badgeable as synthetic, the Mobil One is the real deal. The stuff you buy in the shops is exactly the same as the stuff that goes into a F1 motor, and they do produce a 15W/50 version which the Rover engine is well suited to.
Better still, Mobil package a re-branded version for Halfords, and Halfords sell it a whole lot cheaper - and do 2 for 1 every few months.
