Hello,
This is my first Lexus (2009 rx350). When I start it it sounds a little loud like my lifters, someone said they are probably hydraulic . This is usually only the first start of the day and it usually quiets after a couple of miles. Does anyone have any insight on this? I am hoping this is normal. The car runs and drives great with no other issues. I do run 91 octane and the oil previously in it was a blend. Now switching to full synthetic.ps it has 93,000 miles

 

Couple of things. 1. If it is truly lifters, No it is not normal. 2. Are you sure it isn't piston slap which does happen to some RX 350s. It sounds like a knocking sound, only it's not the connecting rods. It only happens at start up when the engine is cold. Our RX 350, 09, has this problem and had it from when we bought it (58K on the clock). I did a search here and found it does occur with some RXs and there's nothing that can be done. The cause has something to do with clearances in the engine when cold that self correct when the engine is warm. We're using a synthetic mix and do not plan to use a full synthetic.

 

Are you using 0W20 oil? Lexus changed their oil recommendations a few years ago so your owners manual may be out of date. With 5 Q Mobile1 costing $25 at Walmart, it is a no brainier to use synthetic. I have been changing every 10k for many years and the engine looks new inside.

 

My owners Manuel says to use 5w 30. Should I switch to 0w 30? Wouldn't this run thinner and be a little louder? I did find a google response from a lexus mechanic that stated this engine runs a little louder due to hydraulic lifters and something about the injectors. I forgot which engine this was (2gr?) but is this the way the engine is supposed to sound? It almost sounds like a low noise diesel.

 

My second gen that I had for seven years did sound like a diesel at start up especially in the winter. I didn't hear during the test drive and three days that I could have exchanged it.

You will have to live with it and I don't think using synthetic oil will make any noticeable difference but worth a try.

The 3rd gen that I have now sound quieter so maybe Lexus changed the design (or added better noise reduction or both).

 

I put some liqui-moly hydraulic lifter additive in my rx330 recently and the start up noise (3-5 seconds, longer if not driven) completely went away after 600 miles.