Car run on wrong grade oil for years

[vit4]

As above, Mondeo 1.8 with the Duratec HE petrol engine. It's been run on decent 10W40 semi-synth for 8 years or so, instead of the recommended 5W30. It does run absolutely perfect and uses very little oil anyway (less than 200ml over 1000 miles, it's done 112k so nothing too bad IMO!). I want to do an oil & filter change, but what oil grade should I use? Would switching back to 5W30 potentially damage it after so long on the thicker stuff?

Cheers

[Buster73]

I think you've answered your own question.

[matthias73]

No he hasn't.

[226bhp]

No it's unlikely to damage it, but I'd carry on using the slightly thicker stuff given it's an old engine with a fair few miles on it.

[SAS Tom]

It's probably fine. Engines can be run on different grades according to temperature and they usually overlap.

[radiodanno]

You may well find that your oil consumption increases when moving to 5w30.

I'd stick at 10w40 buy maybe go fully synthetic. Halfords are selling it at 4 litres for £10 atm.

[Evil.soup]

I wouldnt imagine it would make a blind bit of difference after all this time. The fact that you are bothering to change it at all is a good thing. Old oil is far worse than an incorrect grade.

On the oil front, if a car runs on 5w 30 and i put in 5w 30 but one recommended for opel MG what difference would it really make if any? Personally i would think none but oil seems to be a minefield these days.

[BFG TERRANO]

I had an 88 escort XR3i. Got it on 66k, used 20W50 and changed it every 5k. Ran sweet and quiet. Sold 7 years later on 150k with no problems what so ever.

[Evil.soup]

I wouldnt imagine it would make a blind bit of difference after all this time. The fact that you are bothering to change it at all is a good thing. Old oil is far worse than an incorrect grade.

On the oil front, if a car runs on 5w 30 and i put in 5w 30 but one recommended for opel MG what difference would it really make if any? Personally i would think none but oil seems to be a minefield these days.

[Ozzie Osmond]

Truth is; modern synthetics are very, very good. Whilst it's always best to use exactly what the manufacturer recommends, arguing the toss between one fancy modern synthetic and another is like debating how many angels can dance on a pin head,

http://en.wikipedia.org/wiki/How_many_angels_can_d...

UK temperatures never go cold enough for the lower figure to make any material difference. And the higher figure is usually more to do with the last millimetre of fuel economy than it is to do with lubrication. Although narrow oilways in the latest engines and fancy OHC valvegear deserve respect.

But really, how hard is it to follow what it says in the manual? Oil change £50. New engine £5,000.

[Justin S]

5w30 was recommended from Ford as the cam followers and valves would have issues on thicker oil, but if it runs fine and a higher mileage unit, stick to the thicker stuff. I had a shed money escort and did an oil change and it had piston slap afterwards. I guess that the previous owners had run something other than 5w30 in it.

[Liquid Tuna]

226bhp said:

No it's unlikely to damage it, but I'd carry on using the slightly thicker stuff given it's an old engine with a fair few miles on it.

This, I reckon too.

[acf8181]

if it ain't broke don't fix it! ;-)

[Buster73]

matthias73 said:

No he hasn't.

112k miles with no problems is the answer.

[TheDoggingFather]

radiodanno said:

You may well find that your oil consumption increases when moving to 5w30.

I'd stick at 10w40 buy maybe go fully synthetic. Halfords are selling it at 4 litres for £10 atm.

Why?

[shovelheadrob]

TheDoggingFather said:

radiodanno said:

Halfords are selling it at 4 litres for £10 atm.

Why?

I'm guessing that they have done a deal on a job lot.

[Shadow R1]

TheDoggingFather said:

radiodanno said:

You may well find that your oil consumption increases when moving to 5w30.

I'd stick at 10w40 buy maybe go fully synthetic. Halfords are selling it at 4 litres for £10 atm.

Why?

Agreed why go fully synthetic, on a high mileage engine that most likely has never seen it before ?

[slippery]

I'd agree with the others who have already recommended that you keep feeding it what it's used to.

[Justin S]

I believe that fully synthetic doesn't burn as much as a mineral oil, as to why fully syn might be a better option.

[Dr Doofenshmirtz]

I'm surprised the tappets don't clatter - they're quite sensitive to using the correct grade oil.