Switching from unknown oil to synthetic

[JGKC9AYC]

I just purchased an '04 Subaru Outback (H6 engine, AT) w/67xxx miles.
I have no idea as to the previous service history.
I drive ~415 miles/week...all 2 lane state routes, 6 stop signs & 4 traffic lights each way.
I don't plan on trying for extended OCI's, but I figure at least 5K miles between changes.
I went to Amsoil's website & they recommend an engine flush before switching to synthetic if the car has over 20k miles.
Is this really necessary?
Is Amsoil overkill for a car that I hope to get 2-300k miles out of? If it is, what would be recommended?
Thanks!

 

[bepperb]

The flush, probably not necessary, but how long were you planning on running it without the flush?

AmsOil will get you to 300,000 miles. Plenty of other oils will, too.

 

[tig1]

Unless the engine is in bad shape I wouldn't flush. A good synt will easily go 10,000 miles. Iv'e been doing it for 31 years.

 

[JGKC9AYC]

Originally Posted By: bepperb
The flush, probably not necessary, but how long were you planning on running it without the flush?


I'm hoping to run it until I have to drive it to the Subaru graveyard like the TV commercial!

Originally Posted By: bepperb

AmsOil will get you to 300,000 miles. Plenty of other oils will, too.


Examples?

 

[Nickdfresh]

How does the oil look now? With a used car, I like to do a "baseline" using a good conventional 5w30 or 10w30 to see how quickly the oil gets dirty.

 

[JGKC9AYC]

It looks ok, but I have no idea on how many miles its' been since the last oil change.

 

[hounddog]

Use a can of Amsoil flush as directed and go from there.I've done such with higher mileage then that several times.Drove the wheels off them using Amsoil products.

 

[JGKC9AYC]

What's the chances of it causing harm to the engine?
50/50? Either it will or it won't?

 

[lipadj46]

What weight oil are your going to use? I've never used an engine flush just MMO for the last 300 miles before an oil change. I would just use a synthetic oil and change at 3k miles the first oil change.

 

[JGKC9AYC]

I'm planning on using 5W30.
I guess I'll go with the PP...too good of a deal to pass up. I just hope it's a decent oil.

 

[lipadj46]

It is a good oil. I have a couple gallons for my corolla. I like mobil 1 high mileage in 5w30 also. I'm not sure if you are interested in 5W-40 in that engine but Rotella 5W-40 synthetic is a popular oil here too.

 

[rclint]

I have never used a Amsoil product, but here is the way I see it. The flush is a product to do two things, make money of course, and also I assume the flush is cheaper than an oil change, so maybe Amsoil seen the market for a product to give the customer a savings, and making a marketable product at the same time.

 

[hounddog]

The FLUSH is advertised to just HELP the old oil to drain more fully.I use at times after extended OCI's. Read the label on the can.its not going to harm a thing or break down big chunks of sludge and stop things up etc.

 

[ZZman]

Flush probably not needed.

Amsoil is overkill if you keep OCI's around 5,000 miles.

PP would be good for that.

 

[JGKC9AYC]

I'd have longer OCI's if I knew the OEM filter could handle it.
According to the maintenance schedule, they recommend an OC every 7500 miles, so I assume the OEM filter's good for that.
I'm just paranoid about using a different oil filter due to specs Subaru has w/the relief valve...no other aftermarket filter comes close to those specs.