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Oil Changes


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A good friend with RX300 (1999 I think) only changes oil every 7500 miles or so. This is nonsynth. oil, almost all city driving, in Georgia. I suggested he go every 3000 miles, but he insists the Lexus owner guide says 7500 is all required for warrenty, now I'm the bad guy after an argument about this. Any other thougts or comments? Thanks

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The owners manual recommends oil changes at either every 5000 or 7500 miles. 5000 would be the heavy duty cycle and 7500 is considered the normal. I see nothing wrong with following the manufacturers recommendation in this case.

My Lexus dealers recommends changes at every 5000, but then again the more they see you the more money they get.

On a side note, on my other truck, a Ford Explorer, I do change the oil approximately every 3000-4000 miles. Ford's recommendation is 3000 miles for heavy duty cycle and 5000 for normal.

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Wow, here in UK we change Oil every 10,000 miles, both for RX-300 and Ford Explorer. We have no extreme temperatures. Lowest say 20 F and highest 80 F with mean average 60 F.

Oil is meant to have been improved over the years. My RX-300 is a Japanese Import and the car is covered in Japanese under the bonnet (hood) and it says 10,000 kilometres which is 6,250 miles. So 7,500 sounds OK, 5,000 a bit paranoid?

Best of Luck


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;) Ok, let me preface this post by saying that I'm not a mechanic and I dont even play one on TV. That said I have learned (primarily from this forum) that:

A.)-By design the engines in early 99-01 RX 300s run hotter than normal. I dont know how much or what "normal" is but there it is.

B.)-Conventional motor oil breaks down with heat & time and turns into sludge. Of course it follows that the hotter your engine runs and the longer you leave a batch of oil in the crankcase the more likely that oil will turn into sludge.

C.)-The biggest rap on the X 300 is the fact that is particularly succeptible(sp?) to sludge, and that the oil should be changed regularly to avoid it.

OK now if you put all these together, to my mind (and this is just my opinion) you should use a synthetic oil (such as Mobil1 or Royal Purple) which is much, much less prone to sludging and you should probably go ahead and change the oil rather regulary to be double sure your not accumulating sludge.

I would also think that by the time you realize that you've got a sludge problem your engine is trashed since I dont think there's a "sludge" light and since we dont have oil pressure gauges its pretty hard to know when the oil sump/pick-up is clogged with the stuff.

Could be wrong but ......

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  • 2 weeks later...

The 3K miles interval was made up by the oil companies here in the states, after all, it does make good business sense. Where as in Europe, the same RX300 the oil change interval is at 10K. Having said this, I do think however, that running 10K on dino oil is a bit of a stretch, I probably would not exceed 5K miles with dino oil.

I have been using synthetic oil ever since the first oil change, it is a little more expensive, but I look at it as fairly cheap insurance for our engine. Syn-oil has a much higher flash point temp., and coking is not as prevalence in our hot running engine, it also has a built in cleaning property.

I prefer to use only synthetic oil, running Valvoline Synpower 5w-40 during the hot summer months, and Mobil 1 5w-30 for the cooler months. If I am to use dino oil in my car, Castrol GT is the only oil that I would consider.

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