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Re: V8-250: Oil - 20W/60

Posted: Thu Aug 08, 2019 4:48 pm
by classiclife
Hello Ian,

I believe the other problem (concerning the dirty engine image) is the amount of undrained oil caught in "Tappet Valley" - I am not sure of the quantity there but it is a noticeable amount. I have heard the suggestion of pouring a litre of new oil in whilst still draining the old, in order to help flush / push through some of the residue trapped. How effective that is I do not know, but I can understand the logic.

Regards.

Richard.

Re: V8-250: Oil - 20W/60

Posted: Fri Aug 09, 2019 4:55 am
by Ian Slade
Hi Richard, I always poured new oil in until it flowed clear at the sump, car was jacked so there was a slight tilt to the drain, the oil stayed bright green for at least 1000 miles.

Re: V8-250: Oil - 20W/60

Posted: Sun Aug 11, 2019 8:54 pm
by tjt77
As regard labelling the Turner V8 a 'dirty' engine :- this is reasonably accurate.. there are only 2 compression rings and early engines had a one piece slotted cast iron oil control ring which is not very effective at its job.... added to fairly high compression ratio, 'blowby' is far more common than with other contemporary engines that have more rings on the piston (jaguars used a 4 rings piston as did most BMC engines from same time period) .. the reason that Turner went with 3 rings pistons is likely that the design was carried over from the highly successful triumph 'speed twin' air cooled engine, which effectively had a dry sump and consequently large oil capacity for its displacement.. Im fairly sure that 'frictional losses' also factored into the design..the power output per litre was VERY good compared with other engines in 1959.. main bearings are also very narrow.. and hence have a short life.. I think its fair to say that these engines were designed to last approx 70-80k miles before requiring overhaul..
anything that gets past the rings and into sump will contaminate the oil making it appear black before its time.. this issue can be reduced somewhat with higher quality/improved design piston rings.. brands such as 'deves' work well..( but require a specific break in regimen) as do the now obsolete( but still readily available in UK ) 'Cords' brand rings..