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Some service advice please

Posted: Tue Nov 25, 2025 4:39 pm
by Quicksilver
Hi Guys

I wonder if you would give me some advice. I have a 2015 Polo GTi that is due for it's yearly service. My garage have said that the recommendation is that the spark plugs should be changed at 10 years or 40,000 miles and the dual clutch transmission oil should be changed at 10 years or 180,000 miles.

Do you think that these are really necessary at this time?

Thanks in advance for your advice

Graham

Re: Some service advice please

Posted: Wed Nov 26, 2025 7:29 pm
by amer6R
transmission fluid should be serviced way sooner

Re: Some service advice please

Posted: Thu Nov 27, 2025 9:35 am
by RUM4MO
I'd be replacing the spark plugs every 4 years if "normal" ones and every 6 years if Iridium tip ones.

Re: Some service advice please

Posted: Sun Dec 07, 2025 1:16 pm
by Quicksilver
Thanks you all for your advice. I will accept the garage suggestion and go ahead.

Re: Some service advice please

Posted: Wed Dec 24, 2025 4:03 pm
by Quicksilver
I replaced the sparks plugs but my garage said that the transmission is sealed so not necessary.

May I take the opportunity of wishing everyone a Merry Christmas and a happy and healthy New Year !

Re: Some service advice please

Posted: Wed Dec 24, 2025 5:40 pm
by Speedhunter
There is no such thing as a “sealed for life” transmission. That term is pure marketing.

Mercedes was one of the first to push this idea. I was working as a service engineer at the time. About two years later, after a large number of failures, they released a service action: oil pans with drain plugs, updated service documentation, software revisions, and actual service intervals. That alone tells you everything you need to know.

Running old, dirty oil full of debris at ~40 bar through a DSG pump, mechatronics valve body, and solenoids is not “maintenance-free” — it’s internal erosion. Magnets for gear position referencing clog up, valves wear, solenoids stick. The damage is slow, but inevitable.

Nothing will make a DQ200 gearbox last forever, but regular oil changes absolutely extend its life. Not changing the oil just guarantees an earlier failure.

Manual gearboxes are less sensitive, but old oil still wears synchros. Ignoring it doesn’t make you smart — it just makes the failure cheaper to ignore until it isn’t.

Re: Some service advice please

Posted: Wed Jan 14, 2026 3:57 pm
by Quicksilver
Thanks for the information Speedhunter. I have only covered 16,000 miles although the car is now eleven years old. Perhaps this is why my garage said the the transmission oil change isn't necessary. What do you think?