Semi-synthetic vs mineral

Hello all,

I know this has been asked before but there never seems to be a definitive answer just a lot of old-wives tales.

I know my engine is clean and sludge free (it was given an ATF flush about 12 months ago).

I know my engine doesn't leak with semi-syn I've used semi-syn in the past when I had to do a quick oil change due to getting a lot of petrol in the oil

If I get some 15w40 or thicker what are the likely consequences? I can't think of any parts in the engine that might be damaged other than by running a too-low viscosity. The local Landy place hands out 15w40 and I think that is semi-syn but can't remember. Trouble is its about and hour out of my way...

I'll probably get mineral, but only if I can find it easily. It's becoming more difficult to find these days if you don't have all day to drive around shops...last lot I got was from a French super-U hypermarket was very cheap but is looking a bit sorry now...

Im pretty sure castrol do mineral oil and its available form Halfords last time I looked. I use semi in mine and its fine. Id like to know whats best as well!!

Halfords do their own branded oil which I was informed by them, is made by Comma. I order mine from Opie Oils online. Decent prices and stock Millers Oils which I like.

Aye, I've used the Halfords stuff in the past but they don't always have it in stock. I think ASDA sometimes have 20/50 mineral as well but not sure if thats one of the *olines or something.

Really, I was just wondering if there's anything in more modern oils that will damage the engine. I know in the past I've put more modern gear oil in (API GL 5 instead of 4) that does damage to the bronze bushings in LR gearboxes. It sticks to them and the bond is so good it actually tears off a layer of bronze when it shears off...though it doesn't seem to have been catastrophic.

dominicbeesley said:

Aye, I've used the Halfords stuff in the past but they don't always have it in stock. I think ASDA sometimes have 20/50 mineral as well but not sure if thats one of the *olines or something.

Really, I was just wondering if there's anything in more modern oils that will damage the engine. I know in the past I've put more modern gear oil in (API GL 5 instead of 4) that does damage to the bronze bushings in LR gearboxes. It sticks to them and the bond is so good it actually tears off a layer of bronze when it shears off...though it doesn't seem to have been catastrophic.

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Best to use the oil engine was designed for. as there are seals/gaskets that can react to different lubes different ways. The tolerances with the bearing etc are set with the viscosity/thickness of the oil at the time engine was made

I've just done an oil change and used 20/50 from asda, engine sounds abit smoother ( probably just because the stuff in before looked as if it could've been original) but seems good to me (oh and it's mineral, and seemed a fair price)

tesco value mineral oil at my local cheapo shop, £1 a litre! yes its crap but for 1500k changes (12 months) it cant be too bad!

I run semi syn 15/40 in the winter for easier life on the starter when it is really cold.
In the summer I run 20/50 mineral and dont notice any difference. I pick my oils up from a local factor usually Comma brand. My VW passat has always used oil to the tune of 1 litre to 300 miles so that gets 20/50 mineral all year round, it has used oil from new and now has 122000 on with no real problems.

vw engines burn oil on purpose to extend service intervals, a brand new golf bought by a colleague back in 2007 came with a 5l tub of oil from the dealer and advice to keep her topped up!

wilkos and lidl (sometimes) do 20/50 mineral oil too - no point pouring expensive stuff in the top just to make smoke and lubricate the road.... :smokin:

Ronsealdeath. You are right about VW engines, I also run a Golf for the Missus and that runs the Passat a close second for oil use. Had both motors new in 2002 so they have had plenty oil over the years !

My vw AQY 2.0 burns oil on new engine between services as do most vw engines

I get 20/50 from my local motor factor cheap, (GT motor factors)

20/50 for most of the older Landies, unless you have done something stupid, and bastardised it by sticking a big 'V' in it!

And mineral is better than the synthetic stuff, as your engine wasn't designed for it!

Think you might have some serious problems if it takes you an hour to get to Copley!!

Second thoughts ... it takes us as long to get from Halifax to Hebden as it does to get from here to Halifax!

Asda are doing 5 litres of their own brand 15w40 mineral oil for 12 quid. I'd buy some if I didn't just get a load from work but it looks good enough to me