Hi! I'm new to this forum, i tried to search the forum for answers, i apologize if these questions already been answered before. For 6 month ago I bought a brand new small Suzuki. I was told by the dealer and by Suzuki HQ that this breakin oil they put into the car at the factory doesn't needed to be changed until next service, which would be the 12month / 9500 miles. I read somewhere that breakin oil should be changed on the 1month / 1000km service, but Suzuki told me that with modern oils it's no longer necessary to change it. How safe it is to run a breakin oil for that long? I was thinking that I might do a change myself, I already have put 4000 miles on the car. Does anyone now how long is a 'short trip' my manual stated that if I do mostly short trips that I need to service the car every 6month / 5000 miles. My trips is usually 3-4 miles and the an according to the temperature gauge my engine hit it's working temperature in less then 2 miles. Does it take longer for the oil to reach the right working temperature? I guess the temperature gauge only monitor the coolant temperature and not the actual oil temperature. Is there a different in fuel economy between dyno oils and syntethic oils (both with the same viscosity) and does Group 4/5 synthetic give better mileage then Group 3 hydrocracked? Read on this page http://cars.lovetoknow.com/Interview:_Synthetic_Oil_Myth that putting synthetic oil in your car engine could boost milage with between 2-5% (but maybe the were comparing a thick dyno oil with a thinner synthetic one, so of course you well get better mileage with less resistance.