Oil Change Interval Concern

With you being a Prius Guru, I would expect you have your oil analyzed to see the effects. Right now I've got both the 2001 and 2007 on extended intervals with routine analysis performed to determine the longest interval with no degradation.

 

Sorry to disappoint.

Here's how I look at it - over 10,000 miles of driving, the Prius uses 220 gallons of fuel (at 45 mpg) and either seven quarts of motor oil (if oil changed 2x) or 3.5 qt of motor oil (if oil changed 1x) during that period. Either way, the motor oil consumption is really trivial compared to the gasoline used.

I can't see spending $20 for an oil analysis to decide whether saving 3.5 qt over 10K miles is worthwhile or not.

 

I've never had any trouble going 7500 miles between changes using synthetic on my other vehicles...and most of that was in the Texas heat. One saw WOT redline daily for 100,000 miles that way without trouble (and it was modded to produce more horsepower.) In the past I've tended to wait until I'm out of powertrain warranty to move over 5000 mile intervals.

With as gently as this Prius is getting used 10,000 mile intervals seems conservative for synthetic.

 

The Prius seems just fine with 16,000 km intervals using Mobil 1 0W-20. Very good used oil analysis. If you want to establish lab baselines, it doesn't hurt. But my experience has been positive

One thing I have *not* experienced was the fuel dilution some have reported. Although a synthetic is a bit more resistant to fuel dilution, the end result is the necessity of much shorter oil change intervals

Only used oil analysis can uncover issues like fuel dilution, or viscosity shearing

 

A discussed previously on PC, I order Mobil 1 large capacity oil filters on line (cheaper than in an auto parts store) in bulk. Same threads, same space, just a larger capacity that provides a tiny bit of insurance on the care of your Prius.

 

Economically, you are right on. In my case, I have two motivations, the first is to minimize waste, significantly. The second is to maintain a car professionally, like any item of very high end machinery. (What better place then PC to get educated.) What is unexpected, is that those two different goals fit together perfectly. High quality oil, periodically sampled, and only replaced when the first signs of oil life ending....and documented results of the engine health.

I bet there is a future business for some mechanics to create a true car HMO and fluid sampling will be a core element of this business.

 

This is another reason why I am going to check my oil with sight/smell/feel. Spending money on oil analysis is not something I think is necessary. Many years have passed that people have employed good old senses to see if the oil needs-a-changin'

I think I am going to go to 20,000 mile interval, using mobil 1 oil and purolator filter.

 

Up to you - I hope that your engine doesn't suffer damage from this.

In a prior msg you indicated that money was tight and that was one reason not to pay for used oil analysis. Should that be the case, you would be better off buying a decent branded mineral motor oil on sale, for around $1 per quart, and changing that oil at 7,500 mile intervals - instead of using full synthetic oil at $5 per quart and changing it at 20,000 mile intervals.

 

I'm about to hit 1500 miles on my new 09 Prius... and figure I'll go ahead and change the oil soon. Probably Mobile 1 or maybe Royal Purple if I can find the right weight locally.

When I hit 5k, I'll probably have the dealer service the car and check the alignment, and then probably have them do every other 5k service. I'll do the rest myself.

It cannot hurt to change your oil early.

 

What part number are you using?