I've changed my oil on my SC300 to Mobil 1 Synthetic. I've read somewhere that if you have an oil leak, it will be worse with the Synthetic oil. Fortunately, I don't have any leaks such as around the valve covers. Since this oil has better lubrication properties, does it mean that you are apt to lose more oil around the rings? It looks like I'm burning around 1 qt. per 1600 miles which seems high to me. I had a BMW when I lived in Germany and 1 qt/1500 miles was not unusual. Most of my trips are short so this may account for the higher consumption since the engine never has a chance to fully warm up. How much oil are y'all using?

 

I had a high mileage (100k) Camry that gulped oil after changing from conventional to synthetic, but the problem went away after the 2nd synthetic change after about four months. I'd try two oil changes worth of synthetic. If the consumption doesn't go down, change back to conventional.

 

I think you should change your piston rings. It is leaking. I'm using Mobil 1 Synthatic. I filled the engine up at full mark and after 3,000 miles, it is still at the full mark.

 

If it is the piston ring leak, use RESTORE it would help. It is not uncommon for higher mileage TOYOTA engines to burn oil anyways, I use CASTROL 5W-50 and it seem to help the oil burning problem better than conventional oil.

 

That is a wonderful suggestion

 

There are several other things you can have them check:

1. Do a compression check (takes a mechanic around 45mins) If the compression is low you need to find out why. Rings can be a problem, you'll see smoke both when you're on the gas and when idling. The smoke is more or less a constant annoyance with rings. More common on the 2JZ is valve stem seals. You'll get a puff of smoke AFTER idling, such as at a stop light. A compression check should only be the first step in deciding to tear down an engine, not the last.

2. Many thought I had bad rings on my car -- low and ragged compression, #4 cylinder low. Ended up being a combination of worn stem seals, and buildup in the valve area causing the valves not to close. This was not a Lexus issue, but a turbo issue on my car- a result of running very rich with not proper fuel control (My fault)

3. Are the spark plugs even, nice and light brown? This can indicate a problem if they are uneven wear from cylinder to cylinder- can show an oil burning problem.

4. Leakdown test - a little more involved than the compression check but does much of the same thing only more. This test can more easily identify which cylinders are leaking and where. You basically blow air into the spark plug hole and measure leakage. You then listen for where the air is escaping. A head gasket problem can be heard through the radiator fill hole, an exhaust valve problem can be heard at the muffler (or exhaust ports if the manifold is off). An intake valve leak can be heard through the intake plenum. Ring leakage can be most heard through the crankcase breather or oil fill hole. Good readings on a compression test on a high mileage engine would be around 75/80. Anything under 70/80 would indicate a lot of wear. A nearly new engine would typically read 78 or 79/80. The first number is basically the amount of psi the cylinder is holding. The second, reference number "80" is the amount of pressure being put into the cylinder. The difference between the two numbers is the leakage.

5. Look for history: Has the car ever run out of coolant? Overheat? Run without oil? Is there anything that would point in any one direction?

 

Thanks for the reply's. I'm familiar with and have used most of the procedures for isolating the origin of the high oil consumption with other cars. This was not an issue until I changed to synthetic. My exhaust is clean relative to smoke and I don't have any leaks around the engine. I topped it off and will continue to monitor and possibly change the oil a little early like around 2500 miles. This is the first batch of synthetic that I've used. The short trips to work (3 miles) can only agravate the problem since the engine hardly warms up so I'd expect greater oil usage. Maybe a higher weight oil. Is Mobil 1 available in other mixes than 10W-30?

 

I wonder if its an interaction between synthetic and dino oil... When you first switched to synthetic, there will be some old oil left, perhaps the seals don't setup as well when there are two different types of oil bases involved. What ever it was, for me the oil consumption eventually returned to normal after the 2nd synthetic oil change --- I'd give it a little more time, and perhaps a 2nd synthetic oil change before returning to dino oil.

I've seen 15w-40 in some other synthetics (Royal Purple), its kind of hard to find, but very good for turbos and race cars. There are some articles out there now that suggest that Mobil 1's new base stock isn't as good as it used to be. I forget the sources, but some people are starting to switch to some more exotic brands (Royal Purple, Redline) to get a better fully synthetic base.

 

Yeah, ummm no... Don't change your rings

I use castrol syntec 5w30 (10w30 in the summer) and usually after 3,000 miles, I need to add around half a quart. Then I change the oil at 4,000 (probably a bit much, but can't hurt it).

Tim

 

I forgot to mention that here in Dallas, they now require emissions testing at every annual inspection at $39 a pop . I had mine done 3 months ago and the emissions were as good as if not better than most new cars according to the garage. That was with the regular oil. I would think that that test would be an effective was to look for oil burning. It sure beats doing a compression test. Anyway, like some of you, I suspect that this will go away after my next oil change. I sure do miss an oil pressure gauge like I had on my Supra. Did or does Lexus have any of their models with oil and amp gauges?

 

I could feel a noticeable difference in compression(power)when I used 10-W40 instead of the 10-W30.
Mobil One also comes in a new formula;0-W30,0-W40,which work very well,actually seemed to work like 20-W50.

 

Not to go off topic, but how do you guys feel about the Mobil blend? Is that like half & half? I have used it before, in my experence it increases engine noise.

 

It looks like what I thought was excessive oil consumption due to synthetic oil may just be an owner's manual error. My Ow. Man. for the SC300 has an oil capacity of 4.1 US quarts with filter change. This is on the inside of the back cover under gas station information. My shop manual for the 93 SC300, on the other hand, lists a capacity of 5.1 qts. w. filter change. I may have used the O.M. capacity which would explain the 1 qt. deficit.

 

Actually, I switched to M1 synthetic a few months ago at about 67k miles and I DID have a loss of just under one quart. Last week the oil level indicator flashed for a split second so I pulled into a Miracle Auto and checked the dipstick. Sure enough I was just over the bottom line, when I remember filling it to the middle of the tab a few months before. I bought two quarts and drained one to bring up my oil level to the middle again. This could possibly be due to the fact that I forgot to put in the oil gasket when doing my last oil change .

 

I have a 99 RX300 AWD in Mexico City. We are 8,000 feet up. I use Mobil 1 15W-50. The higher weight is much better given that the engine needs to work a lot harder up here. However, at about 2,000 miles in after my last change, oil was down about a liter. The mechanics told me this is normal for Mexico City, even with synthetic.