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20/50 oil
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stevel98



Joined: 04 Apr 2014
Posts: 74

PostPosted: Thu Apr 10, 2014 5:09 pm    Post subject: Reply with quote

I use MOBIL 1 Extended life/old car/high mileage 10w60 in everything.

Even after my 2 yearly/20k mile change its still as good as when it was new, to the effect my mate uses it in his MGB as it burns a bit.
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V8 Nutter



Joined: 27 Aug 2012
Posts: 587

PostPosted: Thu Apr 10, 2014 8:37 pm    Post subject: Reply with quote

20/50 oil can sometimes cause problems when starting from cold with hydraulic tappets, the Vauxhall J series was very prone to this. I have seen broken rockers even broken camshafts when the oil pressure has pumped up the tappets.

Some American engines particularly G.M. suffer from misfires when cold because 20/50 pumps up the tappets when cold.
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trampintransit



Joined: 09 Aug 2010
Posts: 166
Location: Edinburgh

PostPosted: Tue Mar 10, 2015 10:16 pm    Post subject: Reply with quote

Now...somebody mentioned 'high zddp' content....refresh me..what's the story there? Modern oils don't contain zinc is that right...whereas older engines need it???
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goneps



Joined: 18 Jun 2013
Posts: 601
Location: Auckland, New Zealand

PostPosted: Wed Mar 11, 2015 5:26 am    Post subject: Reply with quote

From API SF specification the ZDDP additive has been progressively reduced because the platinum in catalytic converters is adversely affected by it. According to information readily found on the 'net, ZDDP is essential to prevent wear in engines which haven't the luxury of modern roller tappets, which eliminate the scuffing and shear of older-style tappets.

Specialists such as Penrite and Millers ensure adequate zinc content in their classic oils, but standard brands cater only for modern cars. Therefore it's unwise to use a standard brand of oil graded API SG or higher in an older vehicle.

Richard
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colwyn500



Joined: 21 Oct 2012
Posts: 1745
Location: Nairn, Scotland

PostPosted: Wed Mar 11, 2015 7:54 am    Post subject: Reply with quote

goneps wrote:
From API SF specification the ZDDP additive has been progressively reduced because the platinum in catalytic converters is adversely affected by it. According to information readily found on the 'net, ZDDP is essential to prevent wear in engines which haven't the luxury of modern roller tappets, which eliminate the scuffing and shear of older-style tappets.

Specialists such as Penrite and Millers ensure adequate zinc content in their classic oils, but standard brands cater only for modern cars. Therefore it's unwise to use a standard brand of oil graded API SG or higher in an older vehicle.

Richartd


Real clarity of explanation there Richard, which everyone should note.
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trampintransit



Joined: 09 Aug 2010
Posts: 166
Location: Edinburgh

PostPosted: Sat Jul 04, 2015 8:18 pm    Post subject: Reply with quote

Right..so..Richards explanation about zinc content is surely enough in itself to choose a 'classic oil' rather than a 'modern oil'...?
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kevin2306



Joined: 01 Jul 2013
Posts: 1359
Location: nr Llangollen, north wales

PostPosted: Sat Jul 04, 2015 8:50 pm    Post subject: Reply with quote

trampintransit wrote:
Right..so..Richards explanation about zinc content is surely enough in itself to choose a 'classic oil' rather than a 'modern oil'...?


For older engines then I'd say yes, I find that all my old cars and bikes run well on the Miller classic 20/50 oils, changed at 3000 Miles or as I do, before the winter layup.

Kev
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ka



Joined: 03 Dec 2007
Posts: 600
Location: Orkney.

PostPosted: Sun Jul 05, 2015 7:01 am    Post subject: Reply with quote

Whilst oil choice in your engine, is to a degree dictated by the engine manufacturers, a basic rule is that modern engines were designed to run on modern oils (synthetic), older engines are designed to run on older style chemistry (mineral).
Choose an oil with the necessary additives to complement the age of the engine, some engines run happily on a straight grade, most on a multi-grade.
Putting a modern synthetic in an old engine may seem a good idea, but is a waste of money. Old engines need regular oil changes, not just because the oil has begun to be broken down, but because of the amount of the contaminants in the oil. If you are draining clear, or opaque oil from the engine, then put it back in, it has not reached, or even nearly reached it's design life, neither has it captured the contaminates that need removing from the engine.
We have a selection of two, and three wheelers, but as most a 'modern' as well. I change the 1.4litres of oil in the Kawasaki at 1000 mile intervals, yes it has a paper filter, but a small oil capacity, and this has 15/40 in it. The Morgan has 20/50, with the zinc content, as this engine has followers running directly on the cam, then to side-valves without a direct oil feed, splash only from the oil gallery in the side of the engine. I have converted the oil passage to leave the engine and flow through an oil cooler, then a traditional oil filter, re-entering the engine in the oil gallery to get to the mains/big ends. I also change at 1000 mile intervals, including the oil filter, again the oil is not 'burnt out' but blackened by the contaminants it is carrying that are too small to be trapped by the filter.
The modern is a 100,000 CDTI Astra, that gets oil and filter changes at 6000 mile intervals. The long life synthetic oil is far from worn out, but like most diesels is as black as the proverbial, and having first hand (well second hand actually as it has been on other peoples cars, who stick to the 20,000 oil change rule) mechanical knowledge of what diesel engine contaminants and sediments do to the plain bearings in the turbo, and the oil feed to it, I will continue removing both oil and contaminates that the filter doesn't.
_________________
KA

Better three than four.
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