I drove my GF's new Mazda3 around for a few minutes this morning to get it warmed up for its first oil change, and made an interesting observation (well, interesting to me at least
). Going by the temperature gauge, it seems to warm up a fair bit faster than my Civic.
I drove it out to the freeway, on the same route I take every morning on the way to work. The temp gauge indicated operating temperature nearly a mile sooner than I see in my car. I wasn't noting the actual temperature (although my Scangauge is hooked up to it) and haven't watched that in my car for a while either but I've also observed that the 3 runs hotter than my car by 7 or 8 degF on the highway, and the temperature (on the SG) varies more actively in different driving conditions than in the Civic (which stays pretty stable except in stop and go in hot weather).
This is interesting to me due to some of the differences between the cars. The Civic:
1) Has a physically smaller engine (less metal).
2) Has less cooling system capacity.
3) Has its catalytic converter mounted vertically in front of the engine, directly connected to the head (i.e. lots of heat right next to the engine).
The only explanations I can think of are:
1) Maybe the temp sensor is just in a different spot between the cars? This is easy to look up but I don't have the service manual for the 3 just yet.
2) Maybe the 3's splash guard keeps the engine more insulated from air currents entering from below? (Civic is open on the bottom).
3) The 3 has an extra .5 liters on the Civic and is burning more fuel, which would create more heat. (Seems like the extra coolant capacity would cancel this out though).
Both have all aluminum engines so that's not an issue. Both seem to have their thermostats in the same place in the cooling circuit as well.
To be clear, I'm not proposing there's a problem here. I just would have expected the difference to swing the other way and thought it was interesting.
I drove it out to the freeway, on the same route I take every morning on the way to work. The temp gauge indicated operating temperature nearly a mile sooner than I see in my car. I wasn't noting the actual temperature (although my Scangauge is hooked up to it) and haven't watched that in my car for a while either but I've also observed that the 3 runs hotter than my car by 7 or 8 degF on the highway, and the temperature (on the SG) varies more actively in different driving conditions than in the Civic (which stays pretty stable except in stop and go in hot weather).
This is interesting to me due to some of the differences between the cars. The Civic:
1) Has a physically smaller engine (less metal).
2) Has less cooling system capacity.
3) Has its catalytic converter mounted vertically in front of the engine, directly connected to the head (i.e. lots of heat right next to the engine).
The only explanations I can think of are:
1) Maybe the temp sensor is just in a different spot between the cars? This is easy to look up but I don't have the service manual for the 3 just yet.
2) Maybe the 3's splash guard keeps the engine more insulated from air currents entering from below? (Civic is open on the bottom).
3) The 3 has an extra .5 liters on the Civic and is burning more fuel, which would create more heat. (Seems like the extra coolant capacity would cancel this out though).
Both have all aluminum engines so that's not an issue. Both seem to have their thermostats in the same place in the cooling circuit as well.
To be clear, I'm not proposing there's a problem here. I just would have expected the difference to swing the other way and thought it was interesting.
