Switching from Conventional to Synthetic

[AndrewB08]

So i recently purchased a 2004 Subaru forester XT with 140,xxx miles on it. I believe the dealership and previous owner were probably using conventional oil in it. I would like to switch it over to synthetic though since its a higher milage car, and its the turbo model. What do you guys recommend as far as making that switch? Should i go to a synthetic blend first and then to a full synthetic or is it ok to go straight to full synthetic? I plan on running Rotella 5w-40 when i go to synthetic in it which is a little heavier then dealer recommended (5w-30). but from what ive read and heard is the best oil for subaru turbo models.

Thanks,
Andrew

 

[HTSS_TR]

You can go straight to synthetic without synthetic blend first then synthetic. Just do a couple shorter OCI's about 4-5k miles then normal OCI of 7-8k miles.

 

[Chris Meutsch]

I've never said this,

WELCOME!

You can switch but you may experience leaks. It's NOT the oil's fault. Just the nature of the switching/cleaning process.

I'd me more worried about some of the gaskets on it vs. changing oil types. It's made it this far..........

 

[sicko]

Originally Posted By: HTSS_TR
You can go straight to synthetic without synthetic blend first then synthetic. Just do a couple shorter OCI's about 4-5k miles then normal OCI of 7-8k miles.


This.

If you're worried about the higher mileage you can use a high mileage synthetic like Valvoline MaxLife, Pennzoil Platinum High Mileage, or M1 High Mileage.

With a turbo Subaru I'm a fan of the Rotella 5w-40, but you can also use M1 0w-40 or Castrol 0w-40. You can also use Castrol 0w-30 which is a thick 30 weight oil.

Unfortunately I can't think of an oil that covers both being a synthetic, and a high mileage oil, that is also a 0w-40 or 5w-40. Turbo Subarus tend to like thicker oils, so you have to take your pick between the 40 weight, or the high mileage oil. Personally, if there are no leaks or issues you're concerned about, I'd just use a 0w/5w-40 and be happy with it.

You can also change out the other fluids too (differentials, transmission, etc), they're easy to do on a Subaru. Is it a stick or an automatic? (I'd love to have a stick shift Subaru Forester Turbo).

 

[Dyusik]

Its not unicorn urine to have to need a ritualistic dance. Just change your oil. To make you feel better the RT6 is a super-conventional. Great stuff. Just fill-er-up and go.

 

[stchman]

Originally Posted By: AndrewB08
So i recently purchased a 2004 Subaru forester XT with 140,xxx miles on it. I believe the dealership and previous owner were probably using conventional oil in it. I would like to switch it over to synthetic though since its a higher milage car, and its the turbo model. What do you guys recommend as far as making that switch? Should i go to a synthetic blend first and then to a full synthetic or is it ok to go straight to full synthetic? I plan on running Rotella 5w-40 when i go to synthetic in it which is a little heavier then dealer recommended (5w-30). but from what ive read and heard is the best oil for subaru turbo models.

Thanks,
Andrew


The best viscosity oil for your car is the viscosity the manufacturer recommends. If Subaru recommends a 5W-30 oil, use that. People try to think that they know more about the engine than the people that actually designed.

As far as conventional vs. synthetic, it is your call. Synthetics aren't that much more $$$ than conventional. If you go synthetic, Mobil 1 5W-30 is a good choice.

 

[BikeWhisperer]

I would recommend either a blend high mileage oil (Maxlife or Pennzoil HM, both are solid) or a full synthetic high mileage (Synpower Maxlife, Pennzoil Platinum HM, or M1 HM). 5w-30 oils are pretty robust these days, so unless there is a fuel dilution issue I'd just stick with the recommended grade.

 

[skyactiv]

Subaru doesn't recommend 5W30 for all driving conditions in their turbo cars of that era. There are plenty of WRX owners that used Mobil1 5W30 and spun a rod bearing. It's as if the turbo Subarus of that era need something that meets the HTHS spec of a VW 502 oil. Use an oil filter that meets the high Subaru PSI bypass spec as not all do.

 

[wemay]

If it was using conventional for 140k miles, this Subaru Turbo did just fine on it. Today's API SN/ILSAC GF-5 oils offer much more turbo protection than any conventional offered in 2004. I would have zero qualms staying the course... or, if you so desire, switching to synthetic, syn-blend.

 

[CT8]

Why change at this time in the cars life.

 

[tojo1968]

Former Subaru Forester Turbo owner. An 06. Ran M1 5w30 until it was traded in at 110k. Zero oil issues except for the infamous Subaru oil consumption.
If I had your vehicle and wanted a 40 weight, M1 0w40 would be my choice over the T6.
I do not have any documentation but have read threads on other forums that using a diesel oil in vehicles that consume oil will foul the cats.

 

[HerrStig]

Originally Posted By: tojo1968
Former Subaru Forester Turbo owner. An 06. Ran M1 5w30 until it was traded in at 110k. Zero oil issues except for the infamous Subaru oil consumption.
If I had your vehicle and wanted a 40 weight, M1 0w40 would be my choice over the T6.
I do not have any documentation but have read threads on other forums that using a diesel oil in vehicles that consume oil will foul the cats.
T6 is also rated SM, a gasoline engine rating.

 

[tojo1968]

Originally Posted By: HerrStig
Originally Posted By: tojo1968
Former Subaru Forester Turbo owner. An 06. Ran M1 5w30 until it was traded in at 110k. Zero oil issues except for the infamous Subaru oil consumption.
If I had your vehicle and wanted a 40 weight, M1 0w40 would be my choice over the T6.
I do not have any documentation but have read threads on other forums that using a diesel oil in vehicles that consume oil will foul the cats.
T6 is also rated SM, a gasoline engine rating.

Yes it is.
But it is marketed as a diesel oil with an elevated zinc level IIRC.
This is why its a cat killer. LOL

 

[JFK]

Non-Issue. Most oil even synthetics are not going to act like a solvent and dissolve old deposits. Most modern engine designs use high density polymers for gaskets not rubber.

If the gaskets are damaged dirt and friction from rotation is the cause. So if switch to synthetic reveals existing damage you have not done any harm by switching. A damaged, dry rotted seal with sludge plugging it is only going to continue to damage the seal.

Deposits in cars if they are large are unstable just like deposits in the human body and even if nothing is done they can break lose, sluff/slough off dissolve etc.Dino oil has more solvents in it then group III or IV synthetics. In fact the initial polarity of dino oil can be fairly high and dino oil was often used as the carrier for additive packages for synthetics.

Deposits with dino are part of rapid oxidation cycle inherent to the product.

 

[wemay]

...inherent to improper maintenance.

 

[ronp]

I've noticed t6 does seem to be the oil of choice amongst the Subaru turbo crowd on Subaru forums I've bumped into as well
I'd get advice/info from them of I were you.theyer the ones with the real world experience with your car type.

 

[AndrewB08]

Thanks everyone for the advice. I think i will just try the switch to Rotella T or T6 and see what happens. From what ive read on subaru forums alot of people recommend the T6. Hopefully all seals are in good condition and hold up to the switch.