My MPG is dropping, could it be the heat?

switch to the 2/60 A/C system!!! might help

He has a Jetta, so can use the upgraded CFC-free 4/60 system.

Try the 'Slow performance degradation' or 'Clean that MAF!' threads under General Maintenance.

My MPG has been dropping in the last couple of months. I installed an oilguard filter and thought that it should improve the MPG but have had a drop since then from around 48 to 43 or so.

I doubt that the change could be do to the filter, but suspect that it has to do with the balmy Phoenix weather which has been in the 100's.

Is there anything that I can do?

The CFC-free 2/60 and 4/60 a/c methods have been shown to use more fuel at freeway speeds than the refrigerant-based a/c.

The induced aerodynamic drag of having the windows open is usually greater than that put on the engine by the compressor.

Sorry, no other useful suggestions.

I did remove the bottom engine cover and have not placed it back on to make it simpler to inspect the oil line going to the hollow plug. I am doing this for some peace of mind.

I wonder if this is taking an aerodynamic hit on my MPG.

Also, the turbo is sucking 110F air, so I think that this could also impact the mpg.