I have 7.5 litres of fully synthetic Halfords 5-40 oil, I was thinking of using it to flush my 1.9pd before doing a full service. I know it doesn't meet PD standards but would it be ok to run in the engine (not all 7.5l at once of course) for 15-20 minutes before changing to proper PD oil? Seems a shame to waste it as  I bought it in halfords £10 sale for my last car and now have no use for it.

It would be a waste to even bother flushing the engine, you will never get all the old oil out anyhow.

I'd go with the idea, because you'll dilute any residue from the old oil by effectively doing two oil changes in 20 minutes running time.

Shouldn't do any harm, and if you have nothing else to do with the oil why not? Will effectively just dilute the residual dirty oil that is in there.

 

I'd leave the engine overnight after draining the oil, then remove the plug again, you'd be surprised at how much extra oil you can get out that has made its way to the sump.

Thanks guys, will do that then. Just wanted to give it a good flush as it has 160k on it. Would be nice to give it a good clear out.

Actually, if you've not started yet, with 7.5l "spare" you could fill with 3.5l, idle for 15 minutes, drain, refill with 4l, idle for 20 mins, drain and let stand overnight.

I'm just waiting for my opieoil order to arrive then am gonna do just that, great idea thanks!

are you sure its wise to flush an engine with that kind of mileage on ???

 

when i worked at the dealers we never flushed a car with more than 60k on the clock unless we knew it had been flushed before hand

 

i would be tempted to use the oil as  flush rather than a flush

 

just my two cents 

Agree with above.

When I buy a new car I like to flush it as follows:

use a flush such as forte in the original oil and let it run for 20 mins

drain this out and change the oil and filter.

add the new oil then let it run for 30 mins then repeat.

I always use LL3 oil.

I know it's a bit OCD but it gives me peace of mind.

Drain the old oil, spin on a new filter and use the oil you have to refill, all this oil changing is a bit wasteful IMO and unnecessary. 

Good quality oil can retain the longevity of engines. its proven that regular oil changes increase efficiency, economy and performance, just like any service action. if it's ignored it will eventually lead to issues down the line.