2003 Lexus RX 300 oil change interval

Hi James:
This can be tough to answer.

If it were my car, and I drove it out on the highway at least 1-2 times per month, then I’d be inclined to wait till 5000 miles. In the absence of that highway driving, then I’d likely opt for the 3000.

This is an opinion I base on my experiences. Others will have different experiences.

The only way to truly determine this is to send the oil out for an analysis.

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Manufacturer maintenance recommendations are a compromise.
They do not come directly from the designers.
They want end users to get through the warranty period.
They want the vehicle to appear inexpensive to maintain.
They want the schedule to be easy to understand.
There’s room for the savvy owner to make variations.

If I were driving 8 miles in the city every day to reach 3000 miles I’d change the oil in a year, maybe less.
If I were driving weekends 57 miles on the highway I’d maybe push past a year.
If I had garage queens like Jay Leno I’d let 'em go a lot longer.

Circuitsmith and JoeMario: Thank you for a response that directly addresses my question and for content that also provides some helpful guidance.

My faith is restored.

You seem to think the oil is damaged only by water dilution or by running it through the engine.

Every time you start a cold engine, some gasoline washes down the cylinder walls into the crankcase and if you don’t drive the car long enough at one time to boil off the water and the lighter parts of the gasoline they build up in the crankcase. The heavier parts of the gas stay in the oil no matter what you do.

The more gas, the thinner the oil gets. Yes, you renew the oil every oil change so the damage is not cumulative to your oil
but it is cumulative to your engine.

It is your car and your money and I don’t care if you ever change your oil but realize you have voided every engine warranty in the first year of your ownership by not following the time interval.

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I have had this vehicle more than 17 years. Any warranty considerations are long since gone. Part of the reason I am still driving this vehicle is because I don’t drive enough anymore which might raise the warranty issue you mention in a new car. When I do buy a new car, I usually lease it first. During that period, the dealer sets the maintenance requirements and I am careful to comply with those.

Not sure why I keep getting warnings and advice regarding warranty coverage. My question was strictly focused on whether it is safe to delay the oil change until the mileage marker had been reached. It’s a very modest stretch of time. During that period, the car sits undriven in a garage with no moving parts in the engine or otherwise. What damage does delaying the oil change cause under these circumstances was my question. The answer obviously depends on a lot of variables. I appreciated the replies, including yours, that identified some of those variables. I can then assess whether they apply or not to my situation. And, as some have been eager to note, the consequences will be mine—a fact of no consequence to them, as they also note—which are two obvious facts that do not require pointing out. But, thanks, anyway.

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Just wondering why you ask for other peoples opinions when you value yours so highly?


You will get a better answer by using Blackstone Labs to test a sample of your oil. $30 for their standard test. The form you send in with will ask how many miles since the oil was changed. Based on what they find you can determine if you really need to change your oil more or less often.


Excellent info! Thanks! Exactly the kind of guidance I was looking for.

Well that’s your problem. I wasn’t looking for your opinion. I was looking for information and data. You provided some. Not sure yet how valuable it is but I appreciate that input. What I didn’t ask you or anyone else for was your opinion about something you know nothing about; i.e., whether I understand warranty obligations and owner’s manual instructions. That’s not your concern. If you have any information relevant to whether oil can be changed less often under minimal driving conditions, that’s what I was seeking. If you have no such information, or choose not to provide it, that’s fine, too.

You should have figured out by now that this an opinion forum, it is not a research data base, and no one here is being paid to do research for you.

Accept it for what it is, a bunch of people who like cars, working on cars and sharing opinions and experiences gathered over the years.

The manufacturer of your vehicle has already provided maintenance instructions for you that are clear and not at all ambiguous. No one has an obligation or desire to prove scientific,y that you are a special case that the recommendations don’t apply to.

Indeed, there is a sizeable portion of the people here that think that the manufacturers schedules don’t have you changing your oil often enough.


Your own reply refutes your basic assertion that this website is just an opinion forum. As you note, it is also a forum for sharing experiences. That is the element I am interested in. If I wanted unsubstantiated opinion, I would go to Facebook or Twitter. Plenty of it there.

Car Talk provides expertise and knowledge through its newspaper columns and radio shows. But they refer readers/listeners to this community forum as a source of expertise that may also be able to answer automotive questions and do it more quickly. It’s clear they don’t think this forum is just a source of unsubstantiated opinions. And obviously it is, in fact, more than opinions since several persons who have responded to my question were able to understand what I was asking and to provide experience and expertise to answer it. Even you provided more than opinion since you told me that gasoline can also pollute a vehicle’s oil. Let me know if that was just your opinion and not based on any actual knowledge.

Long before this stage of my life, I realized that “official” guidance and directions are not always correct. Sometimes it is even corrupt. I prefer to examine the underlying assumptions of directives and rules to see if they make sense. I accept criticism of the argument that “We’ve always done it that way.” We’d still be living in huts and using horses to pull plows if mankind did not question the way things were being done and seek to find better, more efficient, less expensive ways to do things.

How would you expect for anyone on this general forum to have actual facts regarding whether or not it’s advisable to exceed 12 months on oil changes? That would require a lot of testing. We can offer great advice on what might be needed to fix a certain problem, but that’s not your question.

The simple answer is to either follow the manufacturer’s recommendations, or pay for testing.

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Actually, the question is whether to exceed 4 or 6 months since those are the manufacturer’s recommendations (requirements to keep the warranty coverage).

Experience is directly relevant. Perhaps others in this forum have also extended the time period for oil changes. What were the consequences? Either answer is equally valuable. What might cause harm to oil that is not circulating through the engine? Several respondents in this forum identified possible causes of harm despite lack of use. And one Individual did provide the name of a testing service to actually evaluate the condition of a specific oil.

So this forum is a valuable resource that does not require scientific or engineering analyses to provide useful guidance. How to fix certain problems is a great help to people looking for that kind of assistance. But I think there’s a depository here of a lot of fact-based knowledge, too. Some of us are looking for that.

Anecdotal evidence has very limited value. Depends on the car, the driving, and chance. If that’s fine with you, good luck.

Some people change the oil according to schedule and still lose engines. We just had someone on this forum that claims to go fifty thousand miles between changes and is at almost 200.000 miles.
In my lifetime we have gone from 1000 mile oil changes to 10,000 and engines are lasting longer that ever. Better oil and better engines.

In such ever changing conditions and given the brevity of our lives, one persons experience cannot lead to anything stronger than opinion.

Do I suspect engineers build spme gifhr gscyor into theit recommendations, sure. But what other people are trying tp tell tou is that oil changes are so cheap and engines so expensive that there is little to gain and much to lose in your behavior.

The reason so many people mentioned warranty issues was that you did not mention leasing the cars until later and at first claimed to be extending the oil chabges from the start.

As far as the gasoline dilution, it is common knowledge, has been well documented over many years, and if you doa lot of short trip driving, you can pull the dipsyick and smell it in the oil/

The key word there is… “claims”.
I read that post also, and let’s just say that I’m… skeptical…

My question to begin this thread was in the form of a hypothetical. Most responders assumed I was talking about my own vehicle since I described it. Fair enough but it was an assumption since I stated that the question applies to any vehicle. Leasing the vehicle has nothing to do with it. The confusion is partly my fault because we got off track in discussing warranty coverage requirements.

To be honest, I had forgotten all about the time interval requirement in the owner’s manual for scheduled maintenance. After 17 years of “ownership” (minus 3 years of leasing), I treat the 5,000 mileage requirement as the rule for having these services performed at the dealership and, it turns out, have done so since the first one when I was leasing. That first scheduled maintenance took place at 5,112 miles and 8 months. No objection about being two months late from the dealership (the lessor). The next three scheduled maintenances, including the oil changes, took place at 9.5, 5, and 10 months. After that I purchased the car but continued the practice of following the mileage requirement to determine when to have the maintenance done. Over the 17 years I have owned this SUV, the average time span between servicing has been 8.8 months, well past the 4 or 6 month interval stated in the manual. Since 2015, my wife and I have driven less because of health problems and the intervals between maintenance servicing have been 10, 12, 14, and 12.5 months.

In short, since the beginning, I have disregarded the manual’s time interval guidance and followed the mileage guidance exclusively, although I chose the 5,000 mile standard instead of the 7,500 mile rule which I could have followed based on the type of driving to which this vehicle is subjected.

I have already mentioned that no Lexus mechanic (I have the vehicle serviced only by Lexus dealerships) or service manager has ever expressed concern about exceeding the time intervals between servicing. I have also mentioned that some automotive websites also mention only the mileage requirements for oil changes to avoid engine damage although others, including the Consumer Reports link in this thread, do include the time interval guidance.

So here’s where I end up. Many of you will not agree with my conclusion. No need to rush to tell me so. No need to send me pious “tsk tsks” either or remind me that it is my vehicle and my pocket book.

I don’t think manufacturers who include both a mileage and a time interval guideline for scheduled maintenance are serious about the time interval. It actually doesn’t make sense. It would make sense if it applied only to oil and filter changes but it doesn’t. There is no separate schedule for oil changes. They are included in a list of scheduled maintenance services, many of which address the condition of parts of the vehicle that deteriorate almost exclusively from use; i.e., from being driven. Based on the manufacturer’s assumed driving mileage (1,250 miles/month in my case), some of the planned maintenance services are considerably more extensive (and expensive) than others. This is because at those points in a vehicle’s usage, there is wear and tear expected that may call for repairs. Applying a time interval to this scheme for drivers who are well below the 15,000 miles per year driving level, as I have been, ends up scheduling extensive maintenance services long before they are needed based on projected usage levels. That is not only an unneeded and probably useless extra expense, it also can have the opposite effect of producing a limited maintenance service at a time when a more extensive one should have taken place since servicing is no longer tied to actual usage. The only element of the servicing that makes sense for this is the oil change, which is on the list for maintenance at every service. But if the manufacturers were really concerned about getting the oil changed more frequently for inactive drivers they would create a separate maintenance schedule for it. Of course, then owners would be bringing their vehicles in for at least some servicing (oil and filter change) multiple times a year. Not that appealing for marketing and competitive purposes. And suggesting the owner visit his local “Jiffy Oil Change” is not something any dealership will be keen on for a number of reasons which you can figure out yourselves.

Some may respond (oh, have already, in fact) that failing to get the oil changed according to the specified time interval jeopardizes warranty coverage. I’m a lawyer and I’m going to tell you why that’s not legally correct even if a dealer uses it to deny your coverage in case of a defective engine not caused by tardy oil changes. But, first, my conclusion is that an annual oil change tied to normal vehicle usage of 5,000 miles per year exclusively on city streets and highways will not produce damaging engine sludge nor cause any other vehicle damage. [This is an opinion, old-timer_11, but it is also based on 17 years of experience.] How much longer could I safely go? That was my original question but no one actually tried to answer it. I did get some good guidance and insights, though, and I intend to follow up with the Blackstone Labs test just to confirm my conclusion. If it turns out I’m wrong, I’ll come back here and report the results, assuming I can find this thread again.

Free legal advice: If you have a valid warranty claim, do not be put off by the dealer’s assertion that you failed to follow some maintenance requirement and, therefore, have voided your warranty and lost your legal protection. This is true only if the maintenance requirement you failed to follow actually caused the vehicle damage for which you are seeking warranty coverage. Most states have lemon laws that apply to motor vehicles and most courts are not sympathetic to attempts to evade responsibility by finding some technical but irrelevant violation of the maintenance requirements. Of course, if your delayed oil change actually causes the engine damage, bye bye warranty coverage. My conclusion, however, based on my decades of experience with multiple vehicles, is that an annual oil change will suffice if usage requirements are maintained.

Please note, also, that I am not representing anyone on this thread and my legal opinions are not intended to be the basis for any decisions you may make. You need to consult your own attorney for that.

Thanks, all. It’s been a really good learning experience for me and, despite some bumps in the road, I ended up with a good answer to my question. No need to tell me you disagree.

I should have given you and JoeMario more credit in my conclusion above because you both did, in fact, answer my question. I just took the analysis a little further. I ended up in about the same place you both indicated.

Thanks, again.

It is not the dealership that honors your warranty, but the manufacturer. The dealership and the manufacturer are not going to say anything to you about going too long between changes unless you have a warranty claim.

Your “feeling that manufacturers are not serious about time intervals” is based on what facts?

It does however explain why you do what you do.

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“You both provided the answer I wanted.”

There, I fixed it for you.