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Engine oil

Community Veteran
Posts: 7,912
Thanks: 594
Fixes: 8
Registered: 02-08-2007

Engine oil

I seem to have accumulated a number of  oil containers with a small amount left in the bottom, they are all castrol but cover a range of SAE  from 5 to 15. Some are part synthetic and a couple are magnetic so the question is can I mix the lot together .?
I Guess I have enough for a full oil exchange but could they react to each other in any way?
The workshop manual does recommend a SAE 10 - 40 oil but I guess these type of ratings are more about the average tempatures of the country you live in rather than other reason.
We are talking about a 8 year old car so no problems with warranties but equally I do not want to damage an engine that runs fairly well and burns no oil.
6 REPLIES
Community Veteran
Posts: 6,824
Registered: 27-10-2012

Re: Engine oil

Community Veteran
Posts: 16,834
Thanks: 1,124
Fixes: 13
Registered: 06-11-2007

Re: Engine oil

Cost saving? or just being "environmentally friendly", by not wanting to waste it....
Cost saving?  well now... cost of a Gallon of oil in Supermarket ... about £15....... cost of replacement engine, IF, it goes wrong.....  ? ? ? ? 
Personally, I would dump the lot at the local tip... where they have proper facilities for recycling/disposal....
Always use the Supermarket lowest cost oil in my car.... never, ever, bought GTX or similar at 2 or 3 times the price.... you are only paying for the name and the expensively painted can.... !..
Supermarket oils comply with vehicle manufactures specs, and I have never had any problem with them....
TORPC
Grafter
Posts: 5,163
Registered: 08-12-2013

Re: Engine oil

I have mixed oils together & with no ill affects, in my 12 year old van
That said I do make sure it has regular oil / filters etc change as & as near to required as is viable
I am also with Shutter on this, as there should be no reason not to use Supermarket oils, unless your vehicle is still under warranty & the manufacturers stipulate that it would void the warranty etc
Community Veteran
Posts: 7,912
Thanks: 594
Fixes: 8
Registered: 02-08-2007

Re: Engine oil

Interesting replies ,!
I Have tended to use more expensive oils such as gtx & magnetic even though  most of  the cars I have purchased are at least 7 years old but usually with low mileages.
From a logical point of view I cannot counter the points made about using the cheapest supermarket oils so perhaps I have been taken in by all the hype that better oils such as semi synthetic  offer better engine protection ?
I wonder what type of oil the main dealers use when servicing cars ?
PowerLee
Rising Star
Posts: 543
Thanks: 12
Registered: 12-03-2013

Re: Engine oil

Some engines are very sensitive to the oil spec, put the wrong spec oil in a PSA DV6TED4 engine ( 1.6 HDI 16 valve ) & it wont last long before it ruins the turbo & / or takes the big ends out  Grin
Diesel engines with DPF's fitted need the correct spec low saps oil.
Some petrol engines can suffer from tappet jacking if the wrong spec oil is used.
Whatever engine oil you use just make sure it meets or exceeds the requirements stated by the car manufacturer / in your service book.
Community Veteran
Posts: 16,834
Thanks: 1,124
Fixes: 13
Registered: 06-11-2007

Re: Engine oil

Quote from: PowerLee

Whatever engine oil you use just make sure it meets or exceeds the requirements stated by the car manufacturer / in your service book.

And you will find that info on the side/back of the plastic container that the supermarket sells it in !...  If it isn`t listed there, then don`t use it...  go to a motor factors and ask about their "own brand" or cheapest that DOES meet the spec...