Faults:

I am reserving judgment on this purchase. I am the 3rd owner. The 2nd owner had the transmission fail within the first 12 months and had it rebuilt at an independent shop, not Lexus. He then owned it for another 20,000 miles before I bought it.

The transmission is running well. I dropped the transmission oil pan and checked for metal or other signs of failure. I saw none.

This is not a vehicle for those who can't turn a wrench. Did you hear me? This is not a car for people that cannot wrench.

When I test drove the SUV it ran fine. Minimal rust, no accidents, apparently well maintained by Lexus for the first 130,000 miles at the Lexus dealership. It was in for anything from a light bulb to the A/C compressor and starter failure. There was a gap from 130,000 to 156,000, which is when the transmission died. I felt comfortable with the vehicle.

Since the purchase I have spent $1,300 in parts to correct the deferred maintenance. By my rough estimate, it would have cost $6,000+ had I taken it to Lexus for the repairs. Big difference in costs. I will post my list of parts below.

Be warned, the 99-03 RX300 had a PCV oil guzzling issue. If you are losing oil at highway speeds, it's because the poorly designed rear valve cover does not allow oil to drain back down to the head when the engine is under strong vacuum at highway speeds. The valve cover was redesigned in 2004 and again after that, which helped the oil consumption problem. You can ID the older valve cover by looking at the PCV valve. If it's plastic, it's the bad valve cover. If it's the metal screw in type, you should be okay and it means someone changed it before you bought it.

Which leads me to why you are choosing to use premium gas to stop drivability issues. When you burn oil via the PCV system, it reduces the fuel's octane rating. If you correct the oil ingestion problem, you can run lower octane fuel. I now run 87 octane and get 20 MPG. This oil burning issue also leads to O2 sensor failures. The oil coats the sensor and reduces its reaction times and eventually kills it and the catalytic convertor. It's a must address issue, and any independent shop can install a new rear valve cover for a few hundred dollars.

Another unobvious issue RX300 owners seem to put up with is randomly dimming headlights. It's my opinion that the alternator Lexus used on these vehicles had a faulty voltage regulator. I watched mine idle at 13.5V (in spec) and drop to 12.7V when I gave it gas. What was happening to my RX was that the alternator would just stop charging and then come back on. That's my story, but you will find this is a common story on the web. I bought a new TYC alternator with all new parts and unrelated to Lexus suppliers. My alternator now runs at 14.40V consistently. Don't spend big bucks trying to troubleshoot voltage issues. The alternator will likely test within spec at the auto parts store. The TYC alternator cost only $90 shipped (see below).

I could go on for hours, but there is one more issue that needs to be corrected. Lexus installed a transmission cooler in the worst place possible. In the driver's side fender. It gets no air flow and only adds resistance to oil flow, putting a strain on the transmission oil pump and allowing temperatures to reach well above 220*F. Heat and strain destroys transmission. If the fluid is cooked at 190*F and above, the fluid is only good for a few months. The ideal transmission temp is 160-170*F. Hot enough to vaporized condensation, but cool enough to extend the life of the ATF. I removed the factory trans cooler and put a heavy duty 20,000 BTU B&M 70264 cooler in front of the A/C condenser. The hose was shorter and the fluid is now cooled by the radiator fans all the time. My transmission now runs at 170*F on the highway at 80 mph in 95*F ambient temps. It's a must do if you want your transmission to last.

If you want to avoid oil gelling, use full synthetic oil. Plain and simple. You can save $10 on oil but you risk your $5000 engine. Skip your Starbucks coffee stop for two days and treat your SUV right.

MAF sensor (Denso) (Rockauto) $72.

Radiator (TYC)(Rockauto) $84.

A/C condenser (Denso)(Rockauto) $67.

Radiator cap (Rockauto) $4.

Radiator hoses (2) (Rockauto) $20.

1" foam radiator insulation (Home Depot) $3.

134a refrigerant (2lb) (Menards) $10.

A/C schrader valves (O'Reillys) $13.

A/C vacuum pump (free rental Autozone) $0.

Spark plugs (Denso Long life Iridium) (Rockauto) $36.

Used gen2 valve cover (eBay) $60.

Felpro valve cover gaskets (Rockauto) $15.

Oil control valves Toyota OEM (2) (eBay) $75 Note: same price as Dorman.

Thermostat OEM (local Toyo dealer) $18.

ECT sensor OEM (eBay) $35.

B&M 70264 transmission cooler new (eBay) $80.

Toyota Type4 ATF 10 Qts (local Toyo dealer) $60.

Transmission filter OEM (eBay).

Transmission pan gasket OEM (eBay) $13.

Magnefine filters (2) (eBay) $30.

3/8" transmission hose (O'Reillys) $20.

Hose clamps $7.

Silicone vacuum hoses (eBay) $25.

MaxLife ATF steering fluid 1Qt (Autozone) $6.

Intake plenum gasket OEM (eBay) $11.

Battery ground cable (Autozone) $10.

Used power antenna (Craigslist) $50.

Gear oil Royal Purple 75/90 2Qt (Advance Auto) $18.

Differential drain plug (local Toyo dealer) $6.

Zerex Asian coolant 3 gallons (O'Reillys) $36.

Brake calipers (4) (Rockauto) $165.

ATE type200 brake fluid (Ebay) $20.

Wagner ceramic brake pads (f&r) (Rockauto) $50.

Driver's door lock actuator OEM (eBay) $50.

Spray paint (Advance Auto) $7.

TYC alternator (Rockauto) $111.

General Comments:

For the most part, well built with some poorly designed major components like transmission and PCV valve system.

Faults:

The majority of the problem I encountered were the failure of the VVT sensors on both sides of the engine several times.

The major problem with the vehicle was the transmission. My particular model is all wheel drive. As always occurs with most people having problems with their cars, I searched the Internet for answers to the problems; there were an astonishing amount of problems that are similar to mine. All with transmission problems failing at various mileages, but all with the same result regardless of mileage: failure. Most of the search results were all about the failures and different causes, but not really any solutions other than replacement or rebuild, which is very costly either way. If I'd had this information, I would not have purchased this vehicle to begin with.

General Comments:

In general I was very satisfied with the vehicle's performance, comfort and amenities. Until I started having problems and researched them to find out I wasn't the only one. I think I shall do more research on future automobile purchases. I was blown away by forums that have been formed for specific manufacturer and models with so many problems.

I would advise people to research all purchases of any kind, to find out all you can before deciding on the final product.