2003 Lexus RX 300 oil change interval

I have a 2003 Lexus RX-300 but my question applies to all cars. If the recommended oil change is every year or 5000 miles but I drive only 3000 miles in a year can I wait until I reach 5000 miles?

No, change it at least once a year. That’s why the owners manual says “every 5,000 miles OR 1 year, whichever comes first” (please note the emphasis on the word OR)


What is so hard for people to understand x number of miles or 1 year ?
Actually it is your vehicle so do what ever you want . I just feel sorry for the next owner.

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Thank you pyrolord314 and Volvo_V70 for your prompt responses to my question. Unfortunately, I did not need help in reading. I understand what my owner’s manual and maintenance guides say (neither says “whichever comes first” by the way) but those guides are specifically based on driving a certain number of miles per year. In fact, the manuals therefore call for oil changes every 4-6 months. My type of driving with the Lexus RX-300 actually says change oil every 7,500 miles but I have followed a 5,000 mile schedule to coincide with other scheduled maintenance services. I go back to the dealer and have followed their instructions faithfully. Not once in the 17 years I have owned this great and reliable vehicle has any Lexus mechanic suggested I should follow a different schedule even though the manuals say change oil every 4-6 months (that’s the “or” category). For nearly the entire time of my ownership, oil changes have been more-or-less annually.

My question, which I have now researched in more productive forums, is what is the problem with following the mileage guidance instead of the time guidance. Foods and medicines and even oil have “best by” dates but often can be used after those dates. The importance of the date depends upon the product’s effective life. Mileage identifies oil usage so the deterioration to be expected there is obvious. But what deterioration occurs sitting in a garage? That was my question. I have seen answers pertaining to accumulated water vapor and carbon buildup but I’m not entirely convinced yet. Still, it’s been a year with just 3,500 miles so I will probably go with caution this time.

Speaking to you Volvo_70, you might want to consider Car Talk’s guidelines for responses and drop the snarkiness. It’s just a turn-off on an otherwise useless response.


Like you I will never understand why people want to save a few $$$ now that could turn in to $$$$$ later by not doing it the proper way.

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The reason why service recommendations are XXXX miles OR XX months whichever come first is because the people who designed the car, tested the car and warranty the car have determined that is the best oil change interval. Those guides are not based on you driving a certain miles per year. You are making an assumption the owners manual does not state.

If you drive 3000 miles a year, your trips are likely shorter or have longer intervals between trips. Both allow moisture and acids to build in the oil that would have evaporated off with longer and more frequent drives. The oil has a limited capacity to hold those contaminants in solution. That is affected by time. So change your oil on time rather than mileage.

Allow me to offer you another way to look a this. Changes at 12 months and 3000 miles instead of 20 months at 5000 miles means over a 10 year period of time, you’ll do 10 oil changes instead of 6. 4 extra oil changes. If your changes cost $50, that is $200. A new engine to replace one that seized due to oil sludge costs at least $4000. So $200 extra to save $4000 seems like a very good investment.


Thank you, Mustangman. It’s a good explanation. However, your example of a 10-year effect doesn’t quite work unless there is cumulative damage from the delayed oil changes because whenever you change the oil, be it 12 or 20 months, the engine starts over with fresh oil and no sludge. It may be, however, that there has been some damage to the engine from the presence of water and carbon buildup in oil that has not been heated sufficiently. Still, engine oil is mostly damaged and contaminated by impurities from running it through an operating engine. Hence, changing the oil after a certain number of miles is as simple as noting that the oil has been worn out and needs to be replaced. Oil in an engine not running would seem to be insulated from air by being contained in the crankcase. But I think your point is that the resulting contaminants are there from previous cycles through the engine and exposure then to air. Okay. I would like to see some actual studies of what engine oil damage there actually is after a period of 12 months with limited driving.

You are not correct when you say that I am making an assumption that the owner’s manual does not state. Here is what my 2003 Lexus Owner’s Manual Supplement says on p. 90: “The scheduled maintenance log identifies the maintenance required at each mileage interval and corresponding time interval based on mileage of 1,250 miles per month.” The manual goes on to state that if you drive more miles than this you should have the required maintenance earlier than the projected time period.

For those with angst about the ultimate cost of following only the prescribed mileage limits instead of the time limits, I appreciate your concern. And there is no argument from me that an excess of caution is never a bad idea. But no Lexus service manager has ever expressed a concern and after 114,000 miles over 17 years and mostly annual oil changes, my Lexus RX-300 continues to run smoothly and well.

Nonetheless, I appreciate the advice and am going to give my oil situation careful attention from here forward. Thanks to all who responded with the possible exception of Volvo_V70.

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Yes, the wording is:
If you drive more than 1,250 miles per month, you should obtain maintenance at the indicated mileage interval rather than the indicated time interval.

Though it’s not specifically stated, I believe it is implied that the converse also applies, as in:
“If you drive fewer than 1,250 miles per month, you should obtain maintenance at the indicated time interval rather than the indicated mileage interval.”
In other words “whichever comes first”. Though this phrase may not be used in the Lexus manual, it is used by many other manufacturers.

That’s not necessarily the case. Sludge can build up in various places in the engine and not go away during an oil change. If it builds up enough, problems can ensue.


What is the “indicated time interval” in the manual?

Depending on the schedule followed, it is either 5000 mi/4 months or 7500 mi/6 months.

Yes it does work. Sludge is buildup in the engine that does not come out with the oil change. You are more likely to create waxy-chunky buildup inside the engine that can block oil passages. I’ve torn down a few engines that looked like someone barbecued a pig inside it… and over cooked it. That happens when you don’t change your oil.

I stand corrected. I have never seen a statement like that in an owners manual in any of the 23 cars I’ve owned. None were a Lexus, though.

I’m now baffled by the question. It’s there in black and white. If the OP wants to push it to a year, ok, but no more, for me.

I don’t think that you fully understand the process of sludge formation that results from infrequent oil changes. Sludge is a fairly thick, tarry substance that is not removed by simply draining the oil.


If that is what is printed in the 2003 Lexus manual that seems simple enough for James to understand .

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Time to summarize this discussion. My original question was not what does the owner’s manual say. I am well aware of the official guidance. My question, in fact, referred to the “recommended oil change” so obviously I knew that. I was hoping to get some insights from this car community as to how necessary they considered it to follow the time period recommendations on oil changes when driving fewer miles each year than the manufacturer projects.

We had a brief exchange about whether the manual assumes a certain driving distance per year. My 2003 Lexus Owner’s Manual Supplement explicitly states an assumption of 1,250 miles per year but it doesn’t need to say anything. If there is a parallel time period recommendation for the maintenance service you necessarily have to calculate an assumed periodic mileage usage to arrive at the same date.

We also discussed oil sludge buildup and the damage it can cause. I noted that replacing the oil later than recommended provides fresh oil at that point. Mustangman replied that inadequate oil changes can produce sludge that remains in the engine after an oil change. I don’t question whether it is necessary to ever change oil or to delay such changes for multiple years. That kind of abuse is highly likely to cause engine damage. We cannot know whether my situation is comparable to the “barbecued pig” damage Mustangman has seen unless we compare vehicle quality, driving habits and conditions, and fidelity to each vehicle’s maintenance schedule. I have faithfully followed the mileage recommendations for service of my 2003 Lexus RX-300 since day 1. There are many websites to research this question but note this one: https://driving-tests.org/beginner-drivers/how-to-remove-engine-sludge/. Number one on the 8-point list of things to do to prevent and clean up engine sludge includes this advice: “make sure that your engine’s oil is replaced according to the mileage increments suggested in your owner’s manual.” Nothing there about following the time interval guidance.

My owner’s manual does not have a separate schedule for oil changes. That is part of a broader evaluation of the vehicle at each scheduled maintenance visit. My manual recommends a 5,000 mile/4 month schedule if the vehicle has extensive driving on unpaved or dusty roads, tows a trailer or uses a camper or car-top carrier, or makes repeated trips of less than 5 miles in temperatures below freezing. Otherwise, follow the 7,500/6 month schedule, says the manual. I drive entirely on paved city streets and highways, do not tow anything, and do not have a car-top carrier. I do live in Wisconsin but haven’t made repeated trips below freezing in about 13 years. Nonetheless, because I believe totally in the importance of regular vehicle maintenance, I have always followed the 5,000 mile schedule.

In asking my question, I considered the fact that nearly all foods and medicines (prescription and OTC) have either an expiration date or “best by” date. But it is well known that many of these products are perfectly adequate after those dates. My wife’s doctor told her that medications in solid pill form (e.g., aspirin) usually are fine long after their expiration dates. It is also known that food manufacturers have admitted that some expiration dates are just arbitrarily chosen and have little value in predicting how long a product will be safe and edible. There is also the factor of profit incentive. Manufacturers have a natural incentive to encourage more purchases of their products and one way to do that is to tell consumers they need to purchase more often. Cars are far more complex and expensive than these products (well, maybe not more expensive than the vital ones for which pharmaceutical manufacturers have monopoly power), I understand, but the profit incentive is still worth noting. I have in my workshop quarts of oil from Quaker State and Honda. The Quaker State oil has a 2018 expiration date. If it has not been opened, and looks like it has suffered no quality decline, why is it not safe to use? Or even if it has been opened? The Honda oil has a different set of additives and is intended for small, 4-cycle engines. It has no expiration date at all. So this particular issue involving oil and engines is relevant to the same issue involving foods and drugs.

I am 78 years old and have owned 7 cars in my life. All but the Cadillac were purchased new. I keep my cars for a long time: 66 VW (100,000 miles until the clutch gave out); 73 Oldsmobile (14 years until it was “murdered” by my daughter on her driving test); 78 Ford Fiesta (17 years until aging hips began to object to clutches); 87 Honda (16 years until the Lexus caught my eye); 92 Cadillac Fleetwood (about 10 years until I realized less than 800 miles in six months did not justify garage space); 03 Lexus RX-300 (still going strong with no major problems yet). In all these years, I have always followed the recommended maintenance schedules for mileage, not time interval. I have never had a hint of any problem that would be caused by deteriorated oil.

No automotive maintenance schedule I have ever seen has a separate schedule for oil changes. Scheduled maintenance reflects vehicle usage so that some servicing is much more extensive than other servicing. My owner’s manual, for example, has extensive servicing at 15,000 miles (12 months) and 30,000 miles (2 years). If I am driving only 5,000 miles per year but follow the time guidance, I will get a far more extensive service maintenance than the 5,000 mile (4 month) servicing even though all parts of the vehicle have had only 1/3 the usage that is expected at the 12 month interval. (15,000 miles). This may make sense to you, but it makes no sense to me. Neither, apparently, does it to any service tech or manager that I have dealt with in decades of driving different cars because none has ever asked why I wasn’t following the time interval for maintenance rather than the mileage guidance.

In short, my question was a valid one that should have provoked some thoughtful responses. Instead, I got a lot of superficial answers revealing almost no comprehension of the actual question. Most replies were at least respectful, if unhelpful, and were actually all I should expect from a community forum where all communication is by email and often too brief to fully get a dialogue going. I did learn some things, though (thanks Mustangman and others). And the discussion caused me to do the kind of analysis and research that has enabled me to answer my own question. So, thanks, everyone (except you, Volvo_V70).

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There’s your answer. I fail to understand why that is not clear to you. If you want to push it to a year, go ahead. The replies to your question have been very clear and consistent.

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Thank you , all recognition is appreciated .

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One last thought: regardless of what the vehicle maintenance manuals say, I believe the intent of the mileage or time guidance is aimed at drivers who exceed the assumed driving distance in that period of time and are intended to get the required servicing based on actual usage earlier than would normally be expected.

No, the ‘mileage or time’ guidance is to cover those who drive fewer miles, otherwise all they would need is a ‘change the oil every X,000 miles’ guidance.