Hello all,

New to Lexus and just grabbed a GS350 15 with low miles. Been doing a lot of flushing (diff, oil) and about to have a shop to ATF and plugs. I also ordered a RR tuning, tune and was thinking it would be best to install after the atf/plugs. However, I don’t drive often and could flash tune and the plugs would be replaced before 50 miles on the car. My silly question is…..do I wait until after plug change or install the new toy when I get it and know ecu will relearn. Or, could I just do both and pull batt for ECU to relearn?

Thank you for your time reading the post and any support.

Welcome to Club Lexus! Congratulations on getting a '15 GS 350.

I think our member @jgscott is best to help answer those questions for you.

You can do it any of the ways you stated above. Installing the new plugs 1st would be the best option. I would also include before the plugs some type of spray in or, tank intake cleaner to take advantage of the full tune changes especially with timing.

I hope you are Not about to do a Trans flush instead of a drain and refill? I sent you a pm also.

I keep looking at a GS 350.

The thing is, do I really need to drain the transmission and do all this maintenance with a car that is nine years old?

Searching the Internet and finding this thread on the same day that I started looking for a GS series car made me wonder, should I tune this or just leave this as my daily driver?

No matter what money will go into it because I can’t stop touring with anything that I own

No, you definitely do not...

You can service the Trans, or just drive it till it breaks. Depends on how long you want to keep the car? Is this a 15 GS350 RWD, or AWD? How many miles?

The correct installed Tune will add some pep and snap to the GS. The 8speed GS it will help much more. Do you feel it's under powered right now? If not, just leave it alone. The FBO complete mods will make the GS much faster. Just a Tune is a little more peppy drivability. There is a D3 Tune section in the IS350 performance section, and only one other who just did a Tune to their GS a few months ago here. You should see what the IS crowd thinks.

Did you mean touring in bold above, or Tuning?

It’s tune, but i like to tour(drive).

Yes, my regular shop mechanic worked for Lexus and knows the models very well. 6q of oem atf with pan drop. Going to have him change the plugs and flush breaks as well.

I don’t 100% know the history of the car or the owners that drove it. I will be keeping this car for 10 plus years and I always do the following to cars I keep that long:

20k diff
40k ATF
5k oil
2 years breaks

cheap costs for an extra long life on a car.

2015 AWD with 74k and I really enjoyed my hondata tune from my TSX. It gave a smoother pull (vtec), better rpm shifts and better gas mileage. I am okay with not flashing it….if it will damage the car.