synthetic oil change interval?

But, good engineering practices do relate across all fields.

Ed

you want

that. (wink

JP ... you're 'in-flammable' ;-) I've known you thru numerous oil threads and like myself, only your underarms aren't covered with scar tissue on this subject. ;-)

With all these posts... Alright, here is my 2 cents.. I also have a 99 Camry, purchase brand new in 1999. I have been using Castrol Syntech since it's second oil change. I've been changing the oil around 4500 miles but less then 5250 miles. I guess that translates to 7240.5 kilometers or less then 8447.25 kilometers. (Sorry if I get this wrong). I have now 90,000 miles (144810 kilometers)on my car. Just recently changed the timing belt myself and had to removed the valve cover. I was looking forward to a very clean inside, but to my amazement there was VARNISH everywhere! Other then that, the cam lobes look like they are in great condition. Now I am wondering if this varnish is related to not changing the oil at 3000 miles (4827 km), the oil I am using, or if it is related to that recall for 1999 Camrys in which sludge buildup was a problem.

My guess is to start changing it sooner. After seing this, I have to agree to the earlier post that the oil will not supend dirt particles after being the the engine for a while.

And that's my 2 cents and I hope you find it helpful.

aren't

on

I

the

want

(wink

Frequent oil-changes will boost the oil-manufacturer's income, no doubt, but there are self evident issues here or ones that don't need any tests or trials ie the longer the oil is in an internal combustion engine, the dirtier it becomes due to combustion by-product contamination,..the less viscous due to mechanical shearing of the 'long chain polymers' by the oil-pump and other temperature-related issues and probably much more which includes head-temperature issues with the fuel efficient Toyota Camry motors.

Where does this leave the discussion? In my opinion, at the most basic of observations: the longer the oil stays clean and not subjected to the hostile environments of the internal combustion motor, the better condition it will be in to keep your car's engine in good condition. In other words: change it as often as the cost of oil-changes vs the cost and inconvenience of engine repair is loaded towards the 'oil-change'.

Jason

I'd blame it on the oil. On my farm we used to use only Texaco Ursa Super 15W40 oil in our tractors, changed at 150 hour intervals. I checked the valves bi-yearly, and the insides of the valve cover were alway pristine. A friend convinced me that Rotella T 15W40 was better, after all he was a "big rig" driver. I bought several cases. After using the Rotella, the first time I checked the valves I was shocked. Everyting under the valve cover was coated with a translucent brown film. It wasn't particualrly thick, and probably wasn't hurting anything. However, it bothered the heck out of me and I stopped using the Rotella and reverted to the Ursa. Now I have decided it doesn't matter since who the heck knows who makes either oil. For a few years, Ursa and Rotella were both produced by Equilon Enterprises whih cwas partially owned by Shell and Texaco. Since Texaco merged with Chevron, and sold out it's portion of Equilon, I have no idea who makes what. And besides, my "big rig" buddy has assured me that Rotella is even better than before.

Ed

Castrol Syntec is a mediocre value in motor oils, being a Group III hydrocracked 'synthetic'. Analysis results on

show it to have fairly lousy TBN retention. You could use Mobil 1 for usually about the same price and probably have less deposits. There are higher grade oils out there than Mobil 1, (also more expensive) but unless one has certain conditions that stress the oil more than usual, Mobil 1 is usually good enough.

Obviously one would like to maintain a piece of equipment so that every component wears out at exactly the day targeted to replace that equipment (goodness knows, Honda tried). Unfortunately the manufactures, research institutes, government information sources, and consumer groups find any but the crudest estimate to be beyond their ability (government failure data is valuable, but few consumers have access). Therefore this strategy ends up with the most expensive maintenance procedures. An alternative is to do the minimum maintenance necessary to reach a date much sooner (e.g., end of warranty) and let someone else worry about end of life. Between these two extremes, mathematically, there lies a minimum cost per mile point. While we can't determine the point exactly, we know that either extreme in maintenance is more costly than a middle-of-the-road strategy such as twice a year oil change with conventional oil, junk the car for safety reasons or when non-routine maintenance will cost more than the salvage value. OTOH, maybe you just want a new car.

Glenn

snipped-for-privacy@sonic.net wrote: > Analysis results on

Thanks for the pointer! That site is a great source of science-based information.

That is sad indeed. I had a 1990 Prizm that I used Mobil1 in from the time it had 10k miles until I sold it with 285k miles on it. I've got couple of pictures of the engine (valve cover removed) just before selling the car. The interior was without even a hint of varnish or discoloration.

--

- Philip @ Maximum Torque RPM

SNIP

All synthetic oils aren't created equal and some may leave more deposits in your engine than others. But since synthetics are much superior to dino, they protect your engine better and "dirt" won't be a problem as much as with dino. (Philip, is this correct?). This being said, we should also take into consideration the oil filter. Again, all filters aren't creted equal. I have used one that filters down to 6 microns. So contaminants were reduced to a minimum with it. Oh well...

JP

I cannot speak from any long term experience regarding any synthetic motor oils other than Mobil1. IF what original poster said is true (assuming no mechanical deficiency in his Camry), then certainly Castrol Syntech has some inferiority to Mobil1 (engine cleanliness, ability to suspend contaminants, oxidation resistance).

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- Philip @ Maximum Torque RPM

I have a '98 Camry V6, 98k miles, Mobil-1 5W-30, 6k intevals, with Toyota Denso oil filters.

I had a timing belt problem (I'll comment in another thread) and the upper valve cover was pulled.

I noticed that the spark plug area closest to the cam sprocket had a noticable amount varnishing, but the areas to the right of that plug were pretty clean.

My only explanation aside from the timing belt related problem was that the valve cover has a vent on the right side and a hose leaving it (the proper name for the vent escapes me ATM) and that whole "side" (near the oil pouring spout) was pristine.

I'll switch to 5k intervals for awhile and we'll see if it gets any better.

Jay.

OMG. That's disgusting. Philip has groupies.

May I toss your salad Sir???

'94 XLE V6.

171k miles Every 8000 miles: Mobil One 5w30 and I recently switched from the stock 'Yota filter to a Purolator One. I changed my oil when it looks almost as bad as Valvolene does going in.

Lol!

Jason

First, I'm not a rocket scientist, electrical engineer, farmer, or OTR driver, lol. I've been using/changing Mobil 1 since the mid eighties in my autos at the 5000 mile mark and I'm a youngster (42), compared to others in this forum. But it's funny I find this site today because my wife and I were having this same conversation yesterday on synthetic time change intervals.I reminded her of the Mobil TV commercial back in the 80's that stated "Mobil 1", the 10'000 mile motor oil. I called Mobil yesterday, (got number off website)and asked why they don't advertise as the 10K anymore. I was told something to the effect that they didn't wan't to conflict with vehicle manufacturers recomendations, but that I could run Mobile 1 to 7500 miles and not feel guilty the least little bit. Said that their tests showed continued performance well past the 7500 mark. And at $5.00 a quart I'm going to continue to use the 5000 mark as my minumum change interval and as they say arrive at a happy medium. Hope this info was beneficial. Cheers.

Anyone out there own a 2004/2005 Prius! Do you recommend?