I'm wondering why type of oil others here are using in the 2007 ES 350 - conventional or synthetic? I recently bought mine with 50K miles on it and I'm up for my first oil change - I've heard (some of it wrongly, I'm sure) all kinds of things about using synthetic, including that you can't switch back to conventional because the wear is different, or that it's easier on the engine and improves mileage, or that it's marketing and doesn't make a difference at all. It's twice the price, but I want to take care of my (new to me) baby.

I've always used conventional 10W-30 in my previous car, a 2000 Civic, but this is by far the nicest and most powerful car I've owned, so I want to take care of it. I'm happy to spend the extra $30 twice a year for synthetic if it's actually better, but also don't want to get taken for a ride.

 

I use Castrol GTX 5W-30 and it is dino oil. It was put in my car by the dealer (2010) when I purchased it and also on the 1st free maintenance. I change it every 5000 miles and and it is clean as when I changed it. You could go either way with dino or syn and it shouldn't make any difference.

 

It's all about the "extremes"....as in temperature.
The advantage of "synthetics" is in extreme cold and extreme heat.
Better flow in the cold weather especially at startup and better protection against extreme heat.

As I see you are in AZ, don't think that extreme cold is going to be an issue for you.

When it's 110 degrees in AZ and you're running your air conditioner, the engine is going to get awfully hot in there.
The synthetic will protect the engine better, but of course it does cost a bit more.

I use Mobil 1 5w30 in my ES and use Mobil 1 0w-20 in the RX & CT.

Depending on how miles you drive, the additional expense is negligible on a yearly basis.

In regards to "switching over" from conventional to synthetic, it's not really an issue with the modern oils.

Most important thing about OILS regardless of conv vs synthetic is make sure it gets changed regularly !

 

I am using Castrol 5W-30 Synthetic Blend and I am at 98,000 miles. I change every 5,000 miles even though the oil and filters that I use state 7,500-10,000 miles; that is just not going to happen. I drive mostly city (stop and go) otherwise I would consider straight conventional. I agree with the previous posts that state if you change the oil regularly 5,000 miles with today's oils you really cannot go wrong; with the one caveat that if you are driving hard, towing often or are in harsh driving conditions that you should consider syn blend or full syn.