Use sythetic oil in 2008 Sienna?

[sharkinstx]

I'm getting ready to my first oil change on the Sienna (I've got my Toyota filters and the 64mm filter wrench), and I'm thinking of putting in synthetic (Valvoline SynPower, since I've been a happy 30+ year Valvoline user). The van has 84,000 miles on it, and I have no idea what kind of oil has been run in it before (it was in fleet service with a pharmaceutical rep).

We've all heard the old stories about switching to synthetic in high mileage vehicles causing leaks to start, but I've also heard those are urban legends.

What does everyone else think?

[humanoid]

It's fine, go for it.

[arabianobsession]

+1.
Back in the day, when oil was made differently, you couldn't switch back and forth. Now, it's no big deal and you can switch back and forth every oil change if you really wanted

[sharkinstx]

The FAQ on Valvoline's site, "Motor Oil Myths", confirms the compatibilities between conventional and synthetic oils (I found it earlier this evening). I'd post the link now, but their site is down for maintenance. It did say, however, that they don't recommend changing to synthetic if the vehicle already has oil leaks.

[arabianobsession]

It's not going to hurt the car. It will make the oil leaks more apparent BUT it does NOT make the leak worse.

[bepperb]

Synpower is almost all group 3 "synthetic" oil, it's hydrogen cracked conventional oil. The problems with leaks don't really exist with modern synthetics (which have better seal conditioning than they had 20 years ago) of group 4 or 5, but they certainly don't with a group 3 like SynPower.

It's also a pretty good oil, but really an SM or SN api rated oil is going to be fine for your Sienna.

My two cents, from a long time poster at bobistheoilguy.com

[sharkinstx]

Valvoline's FAQ says they use a combination of Group III and Group IV base stocks.

[bepperb]

I believe it, but I doubt they use much in a 5-30 or 5-20 grade. A group 3 base stock will have a viscosity index between 120 and 140, and the viscosity index of Valvoline 5-30 is probably 145~150, so there really wouldn't be a need for much (if any) to meet specs without it. And I would assume if they were spending the money to do it for any other reason it would be to hit more manufacturer specific specifications which they don't currently (they've been saying they'd meet HTO-06 for years, which would require a better base stock). Really, SynPower is a bargain priced synthetic designed to do a better job than a standard conventional at a modest price increase. It's not RedLine for half the price (which would be all group 4/5), not an extended drain oil.

My Highlander has lived on it for most it's life. Actually, Napa synthetic is the same base oil and can be had cheaply pretty often. But I do switch around a lot (even to conventionals) and seal compatibility is a non-issue at this point. Really, the one seal issue Toyota's seem to have is varnish/sludge forming on the valve stem seals causing them to leak and oil consumption to start... and a synthetic would actually be better at preventing this.

[racerchoi]

Bought my van new in 2005 and have used Mobile 1 Fully Syn. since the 1st oil change and usually change oil after 8000 miles or more. Now have 90K on van with a very strong, clean engine. Old oil looks good on every oil change intervals as well.