I am planning to add STP fuel injector cleaner to fuel tank of my w210 1997 e320. I am hoping to get better performance
Do I need to change engine oil after I consume the fuel in the tank?

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Omar
UAE
1997 silver , Avantgarde
E320 W210
101000 km

You probably won't feel a difference with the STP. I wouldn't worry about the oil change either until it's due.

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1984 300SD Orient Red/ Palomino
1989 560SEC
2016 Mazda 6 6 speed manual
1995 Ford F-150 reg cab 4.9 5speed manual

Try some Chevron Techron which is recommended by MB.
Might take a few applications over a few thousand miles but it should clean up your injectors.
Has nothing to do with the lubrication system as you pour it into an almost empty fuel tank.

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1971 280SL ROADSTER
1988 300CE TWIN TURBO WIDEBODY
1994 E320 CABRIOLET
1999 C43 AMG
2005 G55K AMG
2008 CLK63 AMG BLACK SERIES