95 Ls400 Unleaded Fuel (Question)

[caseyr916]

Hi i recently bought a 95 ls400 and ive noticed some knocking in the engine, and i did some research on this thread, i believe it to be because i have been using 87 octane fuel. If i switch to 91 octane will the knocking stop? and am i able to mix 87 and 91 together in the same tank? Right now im at half a tank of 87, should i just wait till i run out then put in 91? Thanks

[caseyr916]

Anybody have any answers for me?

[1990LS400]

Yes, go ahead and add 91 octane to your tank and use only 91 in the future. The slight difference in cost isn't worth the trouble.

[sha4000]

What Kansas said. You can use 87 if your in a pinch but if you get knock switch back immediately. You must have been using it for a prolonged period of time though.