Brcobrem

This weekend I had to make two 160 mile round trips down the Florida Turnpike in my 2000 RX300 with 35,000 miles on it. This highest hill of the turnpike ride is going over overpasses every five miles or so. So it's basically completely flat and about 15' above sea level. Before getting on the pike, I filled it up with regular gas at 87 octane, as I always do. Regular gas in Florida can have up to 10% ethanol, but it doesn't have to have to have any. I'm betting with the current gas glut, it was straight gasoline. Tire pressure was set on Saturday to 32psi exactly on each tire. I would have liked to set them to 35psi but I didn't have time to refill the air compressor in the garage.

On Saturday morning at 10am it was 55F outside, so I didn't have the AC turned on. I'm driving straight south and there was maybe 10-15 MPH wind coming out of the northwest. I had about 100 lbs of equipment in the cargo space. I got on the turnpike, pressed the pedal up to about 68/69mph on the speedometer, turned on the cruise control, cycled the INFO button to Ave MPH, held in on that INFO button for a couple seconds, and it reset to 00 MPH. In about a mile it read 66.4 MPH steadily. I cycled INFO to Ave MPG, held in on that INFO button for a couple seconds, and it reset to 0 MPG. In about a mile it read ~27 MPG. Over maybe the next 5 or 10 miles it leveled out to where it flipped back and forth between 24.9 and 25.0 MPG for about 60 miles.

On Sunday afternoon, about 2pm, I had to repeat the same trip. It was 77F outside so I had the AC turned on this time to 75F. Again I'm driving south, and the wind was about 10 MPH, but from the east this time. I got on the pike and duplicated the same setup as before. I couldn't get it to exactly 66.4 MPH as on Saturday, but I got it to 66.9 and that was close enough. Ave MPG was 23.7 for about 60 miles. So the math would suggest that the AC grabbed about 1.5 MPG, when compared to Saturday's ~25 MPG.

These are obviously pretty good numbers for a vehicle of that weight and I'm happy to be getting them. Here's what do I attribute this to :
1) Keep a clean air filter.
2) I clean the MAF valve with CRC brand MAF spray cleaner when I change the oil. On my vehicle, it's right on the air cleaner hose and easy as pie to get to.
3) I use Castrol GTX 5w30 with a (little bit oversized) FRAM TG3600 filter. The TG filters are rated for 6k to 10k (ie. more filter area). I change the oil at 3000 miles. I don't care if it takes 3 months or 15 months to get to 3000 miles. Imho, the statements by the oil companies (think American Petroleum Institute) and vehicle dealers that oil must be changed every 3 months, or 3000 miles is pure crap (unless you're doing some severe duty or towing). I have one vehicle in my garage that I drive about 50 mile a year, if that. The oil still looks and smells like new and I haven;t changed it since 2003.
4) I swear by Michelin's "Latitude Tour" tires (stock size for this SUV) and I usually keep them at 35 lbs since I don't mind the tire noise and a bit rougher ride. Note that I did have them at 32 for my tests above and 32 would be recommended in colder climates where you might need the extra traction for snow or mud.
5) I use regular gas. It never pings and my RX300 runs just fine on it (here in the flat lands anyway).
6) I drive conservatively. I don't feel the need to race between every stop light and don't care the guy behind is trying to push me into his rat race.

Hope that helps.

Regards . . .

matts6887

i wish i could get 25mpg!. Im usually lucky if i get 22 and thats if im lucky. I will have to check into the air filter on my 99 300 that ive had for almost a month now(it will be a month in 4 days). But i never checked the air filter to see if needs to be replaced or cleaned so if i get a chance today I will check it. Also, where is that maf sensor so I know what to look for and can someone post a pic as if i have to i will pick up some cleaner for it and go to town on it and see if things get better as far as the mileage goes. Im also not sure when the last time t he plugs were changed but for that i may have to go to a local shop unless they are easy to get to then i may try myself.

wotcham8

I have an 03 RX300 with 77k on it. I average 14.9 MPH and 14.9 MPG. Tires at 35 psi. 91 Octane gas. I did test drive an 05 RX330 with 145k on it. When I checked the average MPG on the RX330 it was 13.7 so that made me feel a little better about the mileage I'm getting.

The fact that you are reporting 25 MPG on an 00 RX300 is fantastic! I wonder if your amazingly low mileage (35k) has a lot to do with it?

jcruise

Apologize for not logging in sooner and updating the thread.
I have a friend that works on all types of imports. He clued me in on that. I first commented to him on the oil leak I had and asked where the typical issue is on this vehicle. He told me to check the oil pan and oil filter which I had checked prior to talking to him and was okay. That is when he mentioned the valve cover gaskets which is a typical issue. He said that if they are okay need to look at the intake manifold then consider the front and rear seal, but he felt this was not likely. Fortunately it was the valve cover seals. I then mentioned the poor city mpg I have been getting. That is when he mentioned how Toyota uses the crankcase pressure throughout warm up and at normal op temp in conjunction with other sensors to manage fuel injection via the ECU.
Not to confuse issues, but I recently have a check engine light on. It is a P0171 and P0125 error codes. Being in Buffalo, NY, and retired, I do not drive this vehicle very much and it is in a garage. My mechanic friend needs to perform a smoke test on the vehicle. He believes it is a vacuum leak issue, probably in the EVAP loop. He recommends performing this test before we begin changing expensive "Bank 1 Air Fuel Ratio Sensor" or any other sensor. I have been checking the sensors with a hand vacuum pump and a 9v battery and so far all the sensors on the EVAP system are okay. I am finding it difficult to use the hand pump to find a leak any where else. I am currently getting terrible fuel mileage. That is because of the P0171 lean bank 1 fault. The ECU it trying to richen the bank 1 lean condition.
The P0125 is a code several vehicles have been getting because of the weather we've been having. We have never had weather this cold, ever. Last night it was -13 degrees and today will be -1 with wind chills to -35. Hopefully, later this week and into next week things will improve.
I am still checking things out. I installed a new gas cap, no change . I cleaned the MAF, which can be performed on the original Toyota unit. Several blogs do not recommend cleaning remanufactured MAF sensors. No change. I did change the PCV valve it was plugged. No change. I documented everything I did for my friend, to try and save him some diagnostics time.
My friend is very busy and will get me in for the diagnostics in the next week. I will update the thread when I learn more.

matts6887

wothcham; I bet you are right when you mention the fact that that persons vehicle with only 35000 mile on it(very low for the age of the vehicle still like brand new) probably could have a lot to do with it because all of the components are probably still practically brand new which really amazes me for having such low mileage on a vehicle that old. But i would guess you are definitely right on that one but this is just me.

Brcobrem

Here's an update to my 2/16/15 post :
I made the same run again yesterday. I ran my test exactly the same way. However . . .
This time I saw the averages of 22.9 MPG on the way south, and then 23.2 MPG on the way back north. The temp this time was about 77F (10-14F warmer than before). The wind was coming out of the SE this time at about the same 10MPH (was out of Northwest last run), so this time I bucked a little head wind on the way south, but got a little push on the way back north.

This is interesting: The humidity yesterday was a normal balmy 79%, where back on 2/15 it was a rare 58%. Back on 2/15 the outside temp was ~10F lower. Cooler drier air then meant it was more dense, and thus had more oxygen, and perhaps a little more horsepower. Maybe we have an engineer here in the forum who would know if this observation is meaningful.

So I'm thinking now that the 25 MPG I saw on 2/15, was a best case scenario. The 22/23 MPG seems to be what I recall seeing most of the time. Next trip I'm going to bump up the tires to the 35psi that I usually keep them at. If the wind is about the same, we'll see if that makes a noticable difference.

Regards . . .

P.S. Here's a pic of the rig I use to put dry air in the tires. A heck of a lot cheaper than trying to go green nitrogen, and gets good enough results (ie. more constant tire pressure over wider temp range) :

mizak82

I get 18.5 miles per gallon. I reset it after every fill up for the last two years. I live in Florida so lots of a/c.

I use 93 octane. I tried 87 for a few weeks and a cel popped on for Evap. Maybe the gas cap wasn't on right. But I stopped put 93 back in it since and had no issues.

Wish it got 20. The down fall of the car I think. So so gas mileage.

Brcobrem

Hi wotcham8, matts6887 and mizak82,

When I report that I'm getting 23-25 MPG, we should keep in mind that my tests are done on a perfectly flat turnpike, with the cruise control set for ~66 MPH, moderate ambient temperatures and winds. I'm testing under what might be considered "ideal" conditions.

Most of my driving is low (0 - 40 MPH) speed around the local town trips. I'll reset the average MPG button tonight and make a note to see what is says on a week or so. As I recall, this kind of driving usually shows about 17MPG. I'll report back when I have a real number.

Regards . . .

flylowguy

I get 22.5 driving it easy, but not real easy.

captdalton

Two tanks of fuel run through this new to me vehicle. Brand spanking new BFG tires. 32 psi. 87 octane petro.

Both times after fill up : 19.19 mpg

My commute starts at near sea level on Dauphin Island, Al and ends in north Mobile County. Mostly interstate. 65-75 mph and 6 miles of closely regulated 50 mph near work.

PSURobert

My wife's 2001 RX300 now gets just under 20 mpg on trips. This past weekend, we did a 500-mile round trip in the rolling countryside of eastern Pennsylvania and northwesten New Jersey. After MAF cleaning with CRC, replacing the iridium plugs with OEM and then converting to Valvoline full synthetic oil and a KN filter, I really didn't see any difference. Our mileage was just under 22 mpg until a year or so ago when the pcv valve clogged up and we experienced high oil consumption (200 miles per quart) and low gas mileage (17 mpg) on a trip to Florida. Three cans of Mopar combustion chamber cleaner since then have improved both oil (1,200 miles per quart) and gas (20 mpg) consumption, but they never returned to the glory days of no oil consumption between changes and 22 mpg. I'm convinced the clogged pcv valve did some ring damage, but I note that nowhere in the owner's manual does the maintenance schedule mention the pcv valve. So this is a cautionary tale to remind others to replace the pcv valve around 90,000 miles.

atowerlexs

Well put, very detailed description of diagnosis options.

captdalton

Thanks for the PCV heads up. Maybe I'll get a chance to tinker a bit this long weekend on the Lexus. I'll replace PCV. Already bought the Valvo Syn. Also changing out air filter.

Brcobrem

Hi RX 1st Gen Forum,

It's been several weeks of only around town driving. For me, that means 25 - 45 MPH local stop and go trips. As promised I'm reporting back with a reality check: Today it said 17.1 MPG average. That's about what I recalled previously for local/city driving, but wasn't certain.

I've attached (below) a clip of the "Fuel Economy Information" from the original window sticker. That should help when pondering your vehicle's numbers.

For a vehicle with no or lower milage, the 19 City and 24 Highway numbers are fairly close to my actual experience on perfectly flat terrain in moderate weather. If Lexus was off at all, it would be on the "City MPG". I'm getting ~17 driving with a light foot. If I decided to drive more aggressively, I'm sure I could drop that to 14-15 with no problem whatsoever.

So there you have it: As the youngsters text these days: YMMV
(Your Milage May Vary)
Very punny huh ?

:-)

hypervish

Those MPG figures are with the old rating system (and no ethanol gas), with the new 2008 EPA rating system which is more accurate the RX is rated as follows:

FWD: 17 City / 19 Combined / 22 Highway
AWD: 16 City/ 18 Combined / 21 Highway