Quote:
Originally Posted by 142 Guy
For your consideration.
If Janet habitually does seasonal oil changes (lighter weight oil in cold weather) or doesn't plan to drive the car in temperatures below 10 C, 20W50 probably works just fine. Once temperatures approach 0 C 20W50 conventional oils get pretty sludge like. That makes starting difficult and although the oil pressure gauge will register lots of pressure on start up, actual oil flow to the bearings is not so great.
I drive my 142 E up to the point that the snow stays so driving in -10C would not be unusual in late October. I run a 5W50 full synthetic year around. The 5W makes cold starts easier and insures good oil flow to the bearings on start up. Full synthetic is more expensive; but, it eliminates the seasonal change and given that I don't drive the car a lot and with a rebuilt engine it does not consume oil, it hasn't been a problem running 2 years between changes. Synthetics have a greater resistance to sludge formation and deposits allowing the extended change interval.
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Some very good points there, one being you've rebuilt your engine and have only run it on synthetic cince new. The molecules in synthetic oils tend to be smaller than their mineral counterparts which can encourage leaks and/or burning on cars with engines that have never been rebuilt and run since new on mineral 20W50 say.
Also in the UK, the climate is much warmer (although at only about 3C here today it doesn't feel it!) so a 5Wxx multigrade is probably a bit too thin for us and again, would encourage leaks/burning.
There is also the argument on a car used mainly for short journeys that the condensation produced when started/while cold doesn't get burned off and contaminates the oil with an acidic mix so even with synthetic, it's probably wise to change the oil at least once a year, regardless of mileage.