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Does this sound like bad lifters or something else?

This is a 2006 IS350 (150K miles). The mechanics said that it sounds like lifters so we tried running a 5 minute flush with the 'Motor Mechanic' engine flush. And afterwards, we added Lucas to the new changed oil. I have been driving for nearly a week and absolutely no change. What can I do?

Also, my dad filled it with non-premium gas for a few months that he had it, would that contribute to this issue?

UPDATE: I have now noticed a change, there is no noise on a cold startup. Noise starts after 3-5 min of warming up the car.

 

It likely has something to do with using normal fuel instead of premium octane. On the IS350, it's not just recommended, its required. 2 months of that will create some knocking.

 

Thanks for reply.

 

+1 for the premium, the high compression ratio on these engines absolutely requires premium. It's not one of those "Runs on 87, but performs best on 91+" cars.

Best case scenario? You'll be fine, it'll eventually go away. Once the early detonation hits the knock sensors, the ECU is supposed to adjust and retard the timing. If it continues, it'll keep retarding the timing until it stops knocking to prevent damage to the engine. I wouldn't consider this entirely fail-proof though. If you want, you can disconnect it from the battery for about 30 minutes, and then see how it sounds after (of course have it filled with premium), it may or may not change. Not guaranteeing anything.

 

Disconnect your battery for 20 minutes and pray it somehow goes away.

Did this noise start during, after, or before the usage of the regular fuel?

 

I don't think it's a major issue but I definitely think it's from your Dad skipping the premium. Accidents happen but hopefully he tosses you some coin for the trouble.

 

I will try this today. Noise started about... a month after using regular gas. I am now back on premium.