Vauxhall - Oil suitability

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Thu 18 Mar 2010 19:55
Vauxhall - Oil suitability - markandchrissie
I recently bought a bulk quantity of 5w/30 fully synthetic oil, aimed at Ford Zetecs etc, which is ACEA rated A1/B1/A5/B5.
I was hoping to also use this in the newer Vauxhalls as well, but according to their recent manuals it states that only oils of grade A3 should be used and A1/A5 oils are "strictly forbidden" and could cause damage.
It seems that the A1/A5 oil has a slightly lower viscosity and is aimed at fuel efficiency but can't find a definitive answer as to why it could be damaging.
Any suggestions would be appreciated, as my local motor factor wants almost double the amount for the A3 rated oil.
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Thu 18 Mar 2010 22:13
Vauxhall - Oil suitability - kithmo

IIRC A5 is better than A3, A1 is fuel economy, A3 is better protection and extended life and A5 is fuel economy with extended life. A1 may be forbidden but I can't see why A5 is.

Aren't Vauxhalls supposed to have 10W/40 oil ?

Edited by kith on 18/03/2010 at 22:15

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Fri 19 Mar 2010 07:45
Vauxhall - Oil suitability - Victorbox

Modern Vauxhalls all use 5W/30 fully synthetic. 10W/40 semi synthetic oil stopped being standard issue about 8-10 years ago. I agree I can't see why a higher spec should be a problem. Service books just say it must meet spec GM-LL-A-025 or GM-LL-B-025 which is their extended drain oil spec. http://www.opieoils.co.uk/c-714-ll-a-025.aspx

Edited by Victorbox on 19/03/2010 at 07:49

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Fri 19 Mar 2010 08:09
Vauxhall - Oil suitability - jc2

Ford spec.is only 5W/30 PART synthetic.Not full.

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Fri 19 Mar 2010 19:54
Vauxhall - Oil suitability - markandchrissie

Found a likely explanation.

It seems that Vauxhall and most other manufacturers require a HTHS (High temperature high shear) rating of more than 3.5, (a3/B3 rated oil), whereas the a1/B1/a5/B5 oils have a lower rating of of 2.9 to 3.5, which could cause oil pressure to drop and accelerated wear on an engine not designed for it.
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