Is oil flushing over maintenance when replacing engine oil?

MinuteNoodles

AdrianC said:

And what were those intervals? 10k...?

12,500 and this is back in 2004.

Robisere

I posted on a similar topic about (I think) 2 years ago. In all my years in the trade, the last 20+ as a workshop foreman, I would never recommend or carry out an engine flush before an oil change. Several times over the years I came across older vehicles with thick, contaminated oil due to either old age or lack of servicing, including oil changes. I would recommend to the customer that I drain the oil, preferably overnight, remove the oil filter and sump, thoroughly clean out the gunk in the bottom of the sump and scavenge filter. Refit sump with a new gasket, new oil filter and fresh oil suitable for the specific engine. With certain OHC engines, remove cam covers and oil the cam gear, replace covers with new gaskets. That provides oil to the upper parts of the engine on starting. Run engine for 5 minutes, check oil level (on level ground), top up if necessary. What "engine flush" does: -

It removes every trace of oil 'varnish' on moving parts that bear upon each other. This varnish plates engine surfaces over time with heat from running engines. When engine flush is drained after running the engine with the flushing fluid, it takes away the varnish with it. Fill up with oil, change filter, run the engine and the upper parts get no lubrication until the scavenge pump in the sump has pumped the oil up. With no varnish on bearing surfaces, there is obviously wear to the upper bearing surfaces. I used to tell customers who were adamant about having an engine flush to either do it themselves, or find another garage.

With the older, contaminated engines that I described, I put it to them that 'This will cost £XX but you will get more years from it. You may wish to consider buying another vehicle.' I also wrote on the Invoice that the engine oil would need another change in 500 miles. Several customers got varying amounts of life from their cars this way. It's all about the economics of motoring: is the state of the car's other mechanical parts and bodywork, worth it?

AdrianC

MinuteNoodles said:

AdrianC said:

And what were those intervals? 10k...?

12,500 and this is back in 2004.

Exactly. Nothing like the 18/20+k intervals we're talking about.