Type of Engine Oil

Hi,
I have 10W/40 Enhanced Mineral Oil in the sump of my Pug 205 1.6 GTI.
Will 10W/40 Semi Synthetic Oil be compatible with the existing oil?
Thanks
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On Fri, 03 Apr 2015 20:35:22 -0700, species8350 wrote:

Yes.
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On 04/04/2015 08:32, Adrian wrote:

Generally agreed, but check that the API / ACEA rating is at least as high as the rating in the handbook.
http://www.driverstechnology.co.uk/oils.htm
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With older vehicles with some types of engine, there may be a bit more to it than that. Some of the better wear preventing additives ain't compatible with catalytic converters so are no longer commonly used. This mainly is a problem with push rod engines, where the tappet loading is higher than modern multi-valve OHC engines. So for some older engines a high zinc older spec oil may be the best.
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On Sat, 04 Apr 2015 15:45:44 +0100, Dave Plowman (News)

Other than Amsoil marketing crap is there any evidence for this? Apart from anything else the loading on a pushrod engines tappets is normally lower than on an OHCs.
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Plenty.

Be interesting why you think that. Ever compressed valve springs?
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On Sun, 05 Apr 2015 00:25:52 +0100, Dave Plowman (News)

Go on then, I've not seen any evidence that any oil complying with a reasonable spec has higher cam wera, all the modern MB specifications require the opposite

Yes.
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Modern engines are invariably multi valve OHC types. The loading at the actual cam is therefore very much lower. Pushrod engines have heavier tappets, pushrods, (single) valves. All that weight and inertia requires stronger springs and therefore much higher loading at the tappet/cam face.

Well, you'll have noticed that the springs on a multi-valve type are much easier to compress than pushrod ones, on a similar sized engine.
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On Mon, 06 Apr 2015 00:03:54 +0100, Dave Plowman (News)

Which would be fine if it was true but in general they don't have lighter springs or lower loadings. The extra weight & lack of stiffness is what limits your revs & why they're outmoded, not the increased tappet wear.

Not particularly & they've often got smaller cam lobes with more agressive timings. Not that it's relevant as the wear standards have got tighter for modern oils not slacker.
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The vast majority of engines in daily use by the average driver never get anywhere close to their rev limit.
I'm not attempting to defend pushrod designs. Although the lack of a cam belt might make them remembered by some with affection.
All I will say is it's well enough documented that modern oils will cause very premature cam wear on some pushrod engines. Don't really care if you believe this or not. ;-)
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On Mon, 06 Apr 2015 11:27:37 +0100, Dave Plowman (News)

Which doesn't alter the fact that a Honda VTEC's got stiffer springs & higher loads than a Rover V8 and both of them will go near the rev limiit iif you floor an automatic gearbox.

That's my point, it's not well documented, there's a vast array of documentation that modern oils have better wear characteristics (even to the extent of specifically testing wear on an old style pushrod & tappet engine) and then there's some people on the internet who are upset that the only ep additive they know the name of isn't in there much anymore.
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What oil is specified for a VTEC? How long do the cams last?

Can you give details? There's plenty documentation out there that ZDDP ceased to be used because of cats. But not that a better alternative was found which was cat friendly.

Do you have personal experience that modern oils are just fine on all older engines?
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On Tue, 07 Apr 2015 11:21:16 +0100, Dave Plowman (News)

Sequence iiiG for the US or MB229.1 sets lower wear liiits than all the previus ones

HOw would one know that it's the new oil that caused ones ancient engine to wear out? The major influence on scuffing wear is break in, perhaps somebody could devise a test to measure it & then test a lot of engines against it. Then they could call it a published oil standard and one could check if the oil one was buying conformed to it.
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Now that is 'marketing crap'. ;-)
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On 04/04/2015 15:45, Dave Plowman (News) wrote:

The OP didn't quote a year for his Pug but I'd have thought it was past that period. Pug Owners' groups sometimes good for stuff like this.
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On Sat, 04 Apr 2015 14:41:06 +0100, newshound wrote:

It's a 1980s car.
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An 8 valve OHC, then? I'd ask about the best oil on the Club forum, etc. It may be it is happy with modern oils.
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species8350 wrote:

You can mix the two personally i wouldnt though
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On Saturday, April 4, 2015 at 4:35:23 AM UTC+1, species8350 wrote:

Thanks to all for responding to my post.
Someone asked about the year of my Pug. It is F reg (1989)
Someone else mentioned API/ACEA. I am not familiar with theses abbreviations, neither is the manual. The manual says: Multigrade engine oil viscosity SAE 10W/40 or 15W/40. Duckhams recommend Duckhams OXR Hypergrade or 10W/40 Motor oil.
I hope I can mix them since I have the Semi Synthetic Oil to add.
Best wishes.
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wrote:

So it's designed to run with API SF but everybody used SG or better for the anti sludging spec. You'll have to try quite hard to buy anything less than SM spec though.
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