Synthetic oil & camshaft wear

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I seem to recall reading that synthetic oil (Mobil 1 in this instance) usage virtually eliminates camshaft lobe wear in a dual overhead camshaft engine, such as the Toyota 3.0 V-6. Therefore, the need for the valve lash adjustment is negated. I have 133,000 miles on the engine and it performs like it always did. No oil usage at 5K oil changes and 30 MPG at 75 on the open road (little traffic out here in the West). I've never adjusted the valves. The engine is super smooth running. Do I need to check the adjustment, or is it just a waste of time?
 
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not necessarily a waste of time, there are two places for an overhead cam to wear between the lobe and bucket witch will increase clearance, good clean oil will help here, and between the valve and valve seat witch decreases clearance a much more dangerous situation, only fuel additives will help here, on the Toyota 4.5L I-6 it just requires a new valve cover gasket spark plug hole seals and a feeler gage and a few hours to check it not much for piece of mind IMO
 
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quote:
Originally posted by flathead6: .... Do I need to check the adjustment, or is it just a waste of time?
Do you change your tires before you're riding on the rim?
 
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My dad had his done at (1995 Tacom 2.7 I4)130,000 or 150,000 miles. The Toyota tech. insisted that his engine did not need it but at my Dads insisteded they do it anyway. I think they ended up adding one shim to one valve. The rest checked out fine. My Dad has ran M1 15W50 in warm months and M1 10W30 dureing winter since new with only 1 or 2 exceptions (Penzoil Synthetic). Turned out to be one of his timeing chain tensioners makeing the noise by not properly tensioning one of the timeing chains! My Camry does not even make a provision for adjustment it is shimless bucket set up. I do not think that it is the use of synthetic oil alone. I think that a lot of synthetics have a robust additive package that also helps. If you combine the better additive package with a cleaner envirment due to less deposits it all add's up. If the engine is still running quitely and has good performance it is probably ok. If the UOA is not showing any problems this is also a good indicator that it is fine. Your valve train will get noticeable noiser, performance will drop, fuel millage usualy suffers and insoluables go up as well! If money is not an issue then go for it! It is always a good idea to at lest get it checked! If money is an issues and none of the above symptoms applies to you then you can safely leave it well enough alone for the time being! Recesion is not a common problem on Toyotas with your millage. It is possable but not likely!
 
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I've got a 2000 Sienna. It's had 5k OCI M1 5w30 (ss and ts) from 1st change on. At 85k, I brought in, and the dealer insisted it needed to have valve clearances checked. They then said they made adjustments on 2 valves. It's a very weird issue with the Sienna.... at the time I surveyed 6 dealers in the area. 2 insisted regular valve clearance checks were "critical", and 4 said there was no reason to do them. Pointing out the issue to Toyota corporate was useless. I whined and got quite a bit of my money back. Still not sure if the Sienna needs valves checked or not. Anyway, sorry for the rant. Bottomline, dealer told me adjustments were made at 85k, despite consistent M1 use.
 
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Its not the widening of the gap you need to be concerned about. Over time the valve bangs against the seat and can then recede up farther, pushing up against the cam lobe. Sometimes the clearance is eliminated to the point where the valve is held slightly open and burns (since it is cooled by tranferring heat to the head at the seat). Don't know how susceptible the Toyotas are to this. [ June 05, 2004, 12:15 AM: Message edited by: Geoff ]
 
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