is it safe to add stp complete fuel system cleaner
 

in the manuel for the 2002 s40 mentions not to use over the counter cleaners

anyone uses these...have never cleaned my fuel injection and notice my gas milage can be better
noticed at our local autoshop they have
stp complete fuel system cleaner that adds to the gas
will this harm the car
thanks
have 170,000 kms

I'm not too big of a fan of STP products. The STP shouldn't harm it from my experience and I've used it many times before, its just not my favorite. I prefer Lucas products and 44k. When I first bought my 1999 s70 I tried a can of 44k before a long road trip and it made such a difference, well worth the 20 bucks it costs. If you think that is too much, try the Lucas cleaners, they still work wonders at a better price. If you want to increase your gas millage a little more, you could also add an anti friction/compression oil additive, Lubro Molly products are the best in that department in my opinion. I always use a fuel system cleaner before a long road trip and every oil change I put a Lubro Molly MoS2 anti-friction engine treatment and my 210,000 km engine runs beautifully.