Need to decide on synthetic oil: price versus performance

For what it's worth, the Prius manual says to use normal, non-synthetic oil, and only change every 5000 miles (and that you can use 87 octane gas too, as long as I'm quoting advantages)

I imagine that the reason is that synthetic oil is best at high temps (?), and the Prius engine doesn't get all that hot (I've gotten home after a 20-mile, 40-minute drive to find the hood still iced over...)

 

Flushing an engine only makes the sludge shiny.

 

So is it worth it to use synthetic, then? I figure the difference in price will be something like $30/year if I don't use top-of-the-line synthetic... Happy to do that if it improves the car's long-term performance.

(This is probably a general car question, not just a Prius question )

 

I have heard Pat Goss on Motorweek extoll the virtues of using synthetic oil time and time again. It is considerably more expensive than regular dino-oil but will definitely help your Prius ICE live a lot longer and healthier life.

 

3000-mile change the oil companies are pushing is bogus. Some even change synthetic at 3k miles.

Check out this Synthetic Oil Life Study, Mobile 1 vs. Amsoil :

http://neptune.spacebears.com/cars/stories...s/oil-life.html

It's a comprehensive study of how long synthetic oil can go before it needs to be changed.

 

I've used Mobil 1 in my Honda Van (2001 -71000 miles), a 1994 Volvo 960 (161000 miles), a 1989 Volvo 245 (218000 miles, but only the last 175000 miles) and in a new engine for my 1976 MGB.

To date, the engines burn no oil and have compression this is close to original.

Synthetic oil flows freely from extremely cold to extremely warm conditions. On my MG I've noticed that the cold oil pressure is lower and the hot oil pressure is higher than with dino oil (dino was used for break in)

Does it cost more? Probably not if it extends the life of a car by 2 months...it's $24 for a case of 6 quarts in a local discount store (BJ's Wholesale).

Frankly, I'm sold on it.

 

I use Mobil 1 just because it's very well regarded and seems to be the most available synthetic. Costs about $5 per quart. The last time I tried using cheaper produces I ended up mistakenly getting a "synthetic blend" that was not all synthetic, and I felt dirty after that experience

The advantage for me is that it's available at all auto parts stores, including the one around the corner from my oil changer place, so I don't have to buy it in advance and store it. I can just get some on the way to the oil changer place, and that way I know I'm getting fresh oil. I had an oil leak recently (due to the technician not using the right washer) and until it was properly diagnosed I was adding oil regularly. It was great to be using Mobil 1 which was available everywhere because I could always get more on the road.

 

The big features of synthetic oil are are allegedly longer engine life, extended oil change intervals and reduced friction. I have found that after many years of using various synthetics that Redline gave me the most noticable MPG improvement in any of my cars that I used it in (at least 2 to 3 MPG improvement). Next came Mobil 1 and then the synthetic blends (1 to 2 MPG improvement). I have never owned any of these cars long enough to tell any difference in engine protection, but none ever had any engine problems (I usually keep them 250,000 miles before replacing them).

Since Redline is so expensive ($9.00+/qt), I may just stick with Mobil 1 for my Prius. AMSOIL is supposedly good but it is also very expensive like the Redline.

Unless you really want to go to extended oil change intervals to get the most bang for the buck (like 10,000 miles between changes) I would shop around and get Mobil 1 on sale (I've found it on sale for pennies above Dino, on a good day).

 

It's a no brainer. Synthetic oil flows well cold, hot and at "just right" temperatures. It's not new technology, it will help your engine to last - even if it lasts just a couple of more months, the total cost of synthetic over dino will pay for itself.

I've used it in Volvos, a Honda Van and my the new engine in my MGB...

 

As a general note, automotive oils are tested and certified to an SAE rating, currently SJ/SL for the best, which is most. The improvements to conventional oils through the use of improved additives for viscosity enhancement and stability, friction reduction, etc. are well documented and has resulted in the gap between conventional and synthetic which existed 5 or so years ago getting pretty small. However, synthetic oils offer three main benefits over conventional oils: Increased resistance to thermal breakdown, cold point pourability (less wear during start-up), and higher sheer stress capacity which translates into lower friction. This is a product where you get what you pay for. Conventional oils are more than adequate to allow auto manufactures to offer unprecedented powertrain warranties. Most engines go well over 200k miles when properly taken care of. A synthetic oil adds a cushion of protection such that late oil changes or extreme temperature occurences, etc are less likely to result in premature wear. You can't lose either way, however an extra $8.00 every 5k miles to protect a $7 -10K powertrain is a pretty good investment. The security of knowing your oil will never let you down has led me to synthetic oils since 1993.

 

My understanding is that dino-oil drains from the engine block into the crankcase when the engine is off, leaving little or no residue in the block. When you start the car, the cylinders have no lubrication and this is when 90% of the wear happens, before the engine can lubricate itself.

With synthetic, the oil "creeps" much more. It does not completely drain from the engine, so when the car is started, the cylinders are still lubricated, decreasing the wear.

I have used Mobil 1 in previous cars and trucks, and basically doubled my oil change interval (I changed at 6,000 miles instead of 3,000). I have not noticed any problems.

I haven't decided on an interval for my Prius. I drive over 100 miles a day. At 3,000, I'd be changing once a month. I wonder if it would be good to go 3 months/9,000 miles between changes. I hear synthetic is good for 25,000 miles.

 

Prius Maximus,

At the risk of repeating a previous post, check out:
http://neptune.spacebears.com/cars/stories...s/oil-life.html

They have an informal test of synthetic engine oil longevity going on right now. You may be surprised at the results. Personally, I would not go 25,000 miles (I know - I've read all the testimonials, but I have also had friends do very abusive things to their engines on dino, and none blew up, so there is still more to engine oil characteristics than we have yet discovered).

Since our cars have very expensive powertrains, it seems risky to go to such an extreme oil change interval.

That said, its better for the environment to go long on the drain interval - but I wonder if rebuilding an engine prematurely could potentially overcome all those savings?

 

Gen2,

No way I would go 25,000 either, I just heard it was good for that long. But after having gone 6,000 regularly on a V-8 for 95,000 miles with no bad effects, I was wondering whether 9,000 would be stretching it too much.

Thanks for the link. Mobil 1 was good to 18,000 miles. Cutting that in half, it looks like 9,000 miles will be a good interval. The ICE will have less miles than that as it isn't running all the time.

 

That sounds good and safe. I am gping to wait a while before going to an extended interval, just to make sure that all is well (new owner nerves I guess : )

Have all your synthetic oil questions been answered?

 

Except that it will void your warranty. Sure you wanna do that?