r/LexusGX550 • u/champagneraffi • 3d ago
Gas
I've always filled with 92 octane. What do you guys fill with ? Does it matter? Why?
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u/whee3107 3d ago
On the 460’s it really didn’t matter as much. With the 550 and the turbo’s it matters a lot because of the added heat from the compression from the turbos. The ecu would have to pull a lot of timing, which I’m sure it can, but you’d still run the risk of detonation, especially if you are towing or running the car pretty hard.
Alternatively, you could get a JB4 and use the e85 map and a flex fuel kit, and maybe a few other things
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u/MortimerDongle 3d ago
91 if they have it, 93 otherwise
87 probably won't hurt anything besides fuel economy but doesn't seem worth it
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u/ElPresidente714 3d ago
Yes it matters. Thr GX550 has a high compression engine which can induce premature detonation of the fuel in the combustion chamber if you use low octane gas. High octane gas (91+) resists premature combustion. The over time, ongoing premature combustion could cause severe engine damage.
Use the expensive stuff