OK to use synthetic in 159,000 mile Lexus V8?

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Jan 2, 2004
I'm currently running Castrol GTX 10/30, and after reading a few posts about German Castrol Syntec 0W-30, i'm thinking about switching and extending my drain to 6000 miles. How well does the Toyota 1UZ-FE cope with longer drain invertals, and can i make the switch, or do i need to AutoRX the engine first?
Assuming you can on that engine, check out the valvetrain through the oil filler cap. If you don't see significant sludge or varnish, by definition there's not much to clean out, at least not in the top half of the engine. If you DO see contaminants, a cleaning process could be helpful. I've typically sold cars after about 125K miles, with those engines usually quite clean using nothing but dino oil changed at around 5.5K mile intervals. I'm sure there was probably a very thin, stationary film of sludge on the bottom of those oil pans, but this has no impact on engines.
If it has been well maintained, and is not burning or leaking a lot of oil now, no reason not to change it. I'd certainly recommend using a good engine flush before the change. If you don't, or won't, use a flush, keep an eye on oil consumption. If it suddenly increases after a few thousand miles, change the oil filter and top off. Ballpark rule: If you will double the value of either the engine or the car by changing to synthetic, don't do it.
If you want to change to synthetic that is not a problem! The Lexus V8 are probably the very best production V8's on the planet in terms of materials and build quality! I too would recomend that you use this as an opertunity to first clean or flush the inside of the engine out! Auto-RX, Lube Control and Schaffers Nutrea 131 are the cleaners of choice! If you choose not to flush out the engine then reduce the first oil change interval to 4000 miles. The synthetic oil is going to do some cleaning on it's own of all the old contaimanets left behind from revious oils. This extra cleaning will cut the synthetic oils life short the first time! Note that while synthetics can do a litlle bit of cleaning they are not able to clean like the three products mentioned before. The LExus and Toyota V8 typicaly show little wear no matter what oil is used. It appears that the OCI is more important then the oil used in most cases!
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