Hello to everyone. 

 

I am talking about Impreza 2004 1600 (EJ16) Auto .

the vehicle is in a very good shape with 98.000 Kilometers.

 

i  wanted to change my oil viscosity from 10W-40 to 5W-40 100% Synthetic in my next maintenance.

 

in first thought in the maintenance book write that only turbo engine refill 5W-40 and in mine is 10w-40 "Semi-Synthetic" oil.

 

in second thought i know that the 100% synthetic oil is better almost for all engines and the previous owners filled a 5w-40 oil in the past too.

 

i am confused and its important for me to hear what you guys have to say about it.

 

 

 

amithux,

 

A few things to consider before you make up your mind.

 

Your 2004 engine wasn't designed to use fully synthetic oil. It was delivered with ordinary 10w30 dinosaur oil with oil changes expected every 5000 km.  Dinosaur oil is less expensive and will do the job well for the expected life of the engine.

 

Synthetic oils are more expensive, and they say you can extend your oil changes to 7500 km.

 

Here's the issue with using it in an older engine that it was not designed for. Frequently the synthetic oil, which they claim has better lubricating properties, will leak past engine seals, causing engine oil leaks where there were none before. Some people have found it necessary to keep adding oil between oil changes, where it was never necessary before they put in the synthetic.

 

5000 km oil changes, which includes the filter change, rids the engine of the oil pollutants, where the synthetic 7500 km changes keeps those same pollutants flowing around the engine for 2500 km longer. As for the 5w40 .... last time I checked, Israel didn't get any below freezing weather, which is where the 5w40 viscosity would be a necessity.

 

Personally, I wouldn't waste my money on synthetic oil unless ......... the car manufacturer recommended and delivered the car with it in the crankcase. You are throwing your money away otherwise, in my opinion. In many cases a turbo engine would be a good candidate for synthetic oil.

 

The oil companies have done quite a sell job on the sythetic oil advantages propaganda. Just like the car dealerships with their paint protection, and nitrogen fill for the tires. All of them unnecessary upsell profits for the company.

 

But it is your decision to make. My advice is save your money for that next set of tires or a brake job.

first of all thank you for your really satisfy and clear answer.

 

i have another issue with some parts that i wanted to order from Amazon because the prices in israel is higher than usa even with shipping. 

 

the seller say that he dont know to say if the parts like oil filter  ,atf filter ,air filter ,fuel filter are matches to my ej16 engine and to my 4eat trans because this kind of subaru does not sell in america .

 

i hope someone knowing better to say in this forum if the parts are matches or not.

Thanks.

There really isnt a benefit changing to synthetic oil unless you do alot of short trips. Even then i would just do an extra oil change a year.

 

Synthetic oil doesnt cause leaks. What it does is carry off the dirt that was keeping a weak seal from leaking. The seal if it was going to leak, it would with time. I would stick with what has been used in the car.

 

Have you tried Rockauto.com ?