Hello all,
I am new to the club.
a month ago, I bought 2008 Lexus GS350 AWD with 116500 miles on it.
I have problem with the car consuming a lot of gas. Full tank gives me only 210 miles. I have changed all filters along with OEM spark plugs, but there was no improvement. Also, I have changed the O2 sensors. I use the car as a daily ride from home to work and vice versa mixed between city and highway. I have no code in the Dashboard and the average tank is between 13 to 14 mpg.
I am planning to change the Fuel pump and its filter.
Any suggestions or troubleshoots I need to do.

Thank you in advanced.

 

Clean / change MAF sensor. Replace differential fluids. But the only thing to realistically do is keep a light foot.

 

I have cleaned the MAF, and My foot is light. that average is even on the highway

 

Welcome to the club! Congrats on your car!

I wouldnt change the fuel pump, you will just throw money. You dont "need" to replace the fuel filter. My car has 240k miles on an 08 gs350 awd, and I get great gas mileage. Biggest thing for the GS350 is tire psi and the way you drive. For me if I do a long highway trip ill set the rear tire psi to 40 and front to 37psi. The more psi you add the better gas mileage you get, but the ride gets harsher, and you have a chance of not wearing out the tires evenly. Also when driving, try not to stomp the throttle at red lights. Driving gently and keeping the rpms below 2,000 rpms helps greatly with mpgs.

Its good also to clean the throttle body, maf sensor, air filter etc.

Also have you replaced the water pump? This is a common fail point, they usually last up to 100k miles, and if you dont replace them it can, overheat and destroy your engine. The aftermarket pump cost about $90 on rockauto for an aisan brand (its rebranded oem) and only takes a couple of hours to swap. A failing water pump can decrease gas mileage, by adding drag to the engine.

Also these engines its better to change the oil 3,000 miles. Many have gone to 5,000 and over, and have had issue with oil consumption to where the engine builds carbon on the piston rings and burns oil. To me 3,000 is the safest bet, I dont use high dollar oils, just good brands like castrol and I always use oem filters. Other then the water pump, these are solid cars!

 

I really appreciate you for all the information you have provided me. I will change the tire psi and see what will happen. I have no I idea if the previous owner has changed the water pump, but i will do that.
Is there anything I need to know about this car or tips?

 

When you do the water pump, with it serpentine belt/thermostat/idler pulley/ use toyota coolant. Like I mentioned previous you they sell aisan brand. You can look for aisan, denso, for anything aftermarket as thats like oem if not oem rebranded.

Transmssion, you can do a drain and fill two times at the dealership, and on the third drop the pan. These transmissions are sealed, what the dealer or a good toyota/lexus mechanic does drain out of the drain plug usually what comes out is 3-4 quarts of fluid, it gets measured. Then it gets topped off with the same amount. I one do one drain fill now, then 10,000 a second, then after another 10,000 buy an oem transmission filter and drop the pan and have them clean out the magnets inside.