Originally Posted By: Joe1
I've been running Mobil 1 EP 5-30 in my 05 subaru at 10k intervals. The local Wal-Mart did not have EP in stock so I decided to visit AZ and found M07 serial number GC on the shelf. My engine hasn't seized up at 10K intervals on Mobil 1 and there haven't been any signs of sludge in it. Can I run this GC stuff to 10-12 k intervals without doing expensive oil analysis? This stuff is Expen$ive and if I am investing 30 to 35 dollars for an oil change, I would like to get a good return with an extended drain interval.
What model Subaru? I wouldn't run extended OCIs in any Subaru turbo like my 2005 Legacy given Subaru's latest OCI recommendations.
For 2008 SOA has gone to a 3,750 mile, 3.75 month OCI for all turbo engines. This corresponds to the severe duty OCI in your 2005 owners manual. SOA could not make this change retroactive, but the 2008 engines are virtually identical to 2005.
There is a SOA technical bulletin regarding a small filter located inside a banjo bolt on the turbo oil supply line. This filter has no scheduled maintenance interval and isn't real easy to get to.
The bulletin states that this filter should be inspected if the vehicle has been subjected to long OCIs, its last oil change is unknown or if the engine has been subjected to moderate or severe acceleration. (Moderate?)
Oil changes are cheaper than turbo replacements. Your car came with a 5/60 powertrain warranty, including the turbo. Don't blow it with extended OCIs.
$35 oil changes are expensive? Don't make me laugh!