Joined: 27 Apr 2005 Posts: 11735 Location: S. Cheshire
Posted: Wed Mar 14, 2012 7:35 am Post subject:
I'd use a 20/50 to flush it through, then either a straight 30 or more likely a "classic" 20/50 (ie without all the detergents of a modern oil) before using the car properly. But I'm no expert!
R _________________ Rick (Admin. oldclassiccar.co.uk)
Various 1930s-1960s relics - Austin, Morris, Bedford, Dodge etc.
I agree with Rick - I use 20/50 Comma in my 1938 Rover 16 and change it every 1500 miles or 2 years as it has no oil filter other than the sump pump strainer which only removes lumps of coal _________________ Phil
Joined: 26 Nov 2007 Posts: 178 Location: North Warwickshire
Posted: Wed Mar 14, 2012 9:29 pm Post subject:
Phil - Nottingham wrote:
I agree with Rick - I use 20/50 Comma in my 1938 Rover 16 and change it every 1500 miles or 2 years as it has no oil filter other than the sump pump strainer which only removes lumps of coal
Perhaps that's the answer as I can't be doing with coal in the sump. Coca Coala I've tried already.
One of the classic car challenges presented by multi viscosity oils (like 20/50) is that the viscosity is higher then a mono oil (like SAE 30) at high temperatures. That's fine with modern engines with sturdy fuel pumps that can handle high viscosity at high engine speeds, but it poses a challenge for older engines. The design of older engines assumed that the oil will have a low viscosity at high temperatures and high engine speeds.
Many older engines, particularly pre war engines, adopted the "low pressure, lots of oil" approach with the reduced viscosity.
So, if you're confident that the oil pump is sufficiently robust then a multigrade20/50 classic oil (Penrite, Millers, Halfords, Castrol all make them along with many others) is fine. If you suspect that the oil pump is desgned to throw a lot of oil about at low viscosity then use something like a mono SAE 30 classic oil.
I use classic 20/50 in my 1969 Daimler V8 saloon and straight classic SAE 30 in my 1937 Daimler 15 Sports Saloon. _________________ 1937 Daimler 15 Mulliner Sports Saloon & 1969 Daimler V8 250 Saloon
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