oil type and fuel economy

[jayman]

If you've had good results with the M1 5W-30, keep using it

[jayman]

Originally Posted by FrankD

Is it the 0w that gives you the better mileage or the synthetic aspect of the oil?

Running a variety of oils in my '04 Prius, in summer there was no difference running a regular 5W-30, synthetic 5W-30, 0W-30, 0W-20, etc. Average decline of 2 mpg running a heavy duty 15W-40 in *hot* summer weather

Originally Posted by FrankD

In the past I was always afraid to change from dino to synthetic in a "used" engine, but I think I'd do it with the Prius.

I'd be leery too

Originally Posted by FrankD

All my past cars have been non-hybrid cars, and I also used Auto-RX in them.

Some folks swear by Auto RX. I'm unsure how a can of stuff will restore a motor to like new condition. Any product strong enough to dissolve accumulated sludge/varnish is probably strong enough to attack seals and gaskets

I've used high quality heavy duty oils, and synthetic oils, for +25 years now. Even at +300,000 miles, taking off an intake manifold or head to repair a bad gasket, the internals were spotless

[ALS]

Auto-Rx is a excellent investment if you have over 50K on your Prius. It is a metal cleaner that cleans out the varnish and sludge that accumulates in your engine over the years. It will not harm you engine or seals in any way. If your running Dino oil you need to use Auto-Rx.

I used Auto-Rx in my 97 Volvo 960 and saw a 1-1.5 mpg increase during and after the cleaning at 70K. The valve train looked like someone melted a chocolate bar over the camshaft and valve train. After the cleaning the cam and valve train was a shinny as a brand new penny.

I use to be a mineral oil guy for many years then went for synthetics for better mileage. With the CVT transmission I would only use Toyota recommended fluid.

The engine on the other hand I would use a top quality synthetic like Mobil 1, Schaeffer's 9000, Castrol Edge, Redline, Amsoil and even Pennzoil Platinum. Remember the engines in these cars are constantly starting and stopping. I would consider that as severe duty.

Plus using dino and changing every 3K isn't that cost effective over using Synthetic and changing every 5K-6K. When you figure in the cost of your time it is cheaper to use synthetic.

Do the math $23 for four quart jug of Mobil 1 from Wal-Mart and a $5 filter is $28 every 5K miles. $5.60 per 1K miles.

4 quarts of dino oil is $10 and a $5 filter every 3K miles is $5 per 1k miles.

If you drive 15K miles a year it runs $84 to use Mobil 1 using 5K mile oil changes. It costs $75 to use dino oil with 3k mile oil changes. You save $9 using non synthetic oil but you have also used 2 more oil filters and 8 additional quarts of oil doing the 3K oil changes over 5K mile oil changes. Add in the time of two extra oil changes and properly disposing of the extra used oil and it is really worth the time involved.

[FrankD]

Thank you all for this informative thread.

My Toyota dealer changed the oil when I bought the car last month. I've now have driven it about 1000 miles. They used dino 5w-30 and told me it would be due again in 5,000 miles.

Is that correct, or should I change the dino every 3,000 miles like I do in my other cars.

Also, has anyone ever switched to Mobil ! after 50,000 miles of using dino ? Does the possible risk outweigh the benefit?

I have so much to learn about this awesome car!

Thanks! Frank D.

[ALS]

Just drive the car as you normally would and when it is due for it's next oil change at 5K miles you can switch to synthetic. Remember regular oil isn't as forgiving as synthetic when run longer than it should. Quality dino oil today is far superior to what was available just 10 years ago. They are much better due to a modern high tech refining process as well as additive packages that brings the quality way up. 10-15 years ago engine oil was still a 3K mile oil change. Not today the better dino oils can easily go 5K miles with no problems.

At my non Toyota dealer cars that go over 7.5K on dino have sludge issues. I've seen cars with synthetic that get 10K oil changes with no visible evidence of any sludge.

There no problems switching over to synthetic from regular oil.
Many of the horror stories are just that stories. If the engine already leaks oil it still is going to leak with synthetic. If it doesn't leak now it isn't going to start after you switch over.

Synthetic oil is a natural engine cleaner. Over three or four oil changes it will clean out a lot of the crude that builds up in the oil galleries. It may lighten up the varnish but what is left is just a discoloration on the metal.

[ETP]

I do not recommend extra flushing chemicals for any dirty cavity you might have! LOL
Just drain and fill with clean fluids.

[jayman]

Originally Posted by ALS

JSynthetic oil is a natural engine cleaner.

That is due to the esters in synthetic oils. Where you have to be careful is with oils containing high ester levels, in an old motor the carbon/sludge buildup on rotating seals will dissolve, and the seal could leak

If you run a motor from new with synthetic, you will have excellent results even with extended oil changes. I've had enough trouble with older vehicles (Ex Utah Highway Patrol Chevy Caprice with LT1 motor. Switched motor over to Mobil 1, rear main started leaking. Switched rear axle over to synthetic, pinion seal and both axle seals went) that I'm leery of it

[jayman]

Originally Posted by ETP

I do not recommend extra flushing chemicals for any dirty cavity you might have!

Ummmm ..... don't knock it till you try it