At 125,000 miles this motor has plenty of wear on the engine parts. Unless this vehicle has seen consistent oil changes at the scheduled intervals changing to a synthetic oil is not advisable. Why? Synthetic oil is very detergent and its molecular structure as flat not clumpy as for mineral motor oils. This is what makes it slippery and to retain liquid stage at extreme cold temperatures. Synthetic oils are used in jet engine exclusively. I have a 2001 Audi TT Roadster 1.8L 5 speed transmission. Since 2002 it has been serviced with semi synthetic oils. It has 97,000 miles. The engine is as clean as the day it was assembled. There are no leaks and there is minimum oil used between the six month interval. I have a 2008 Mercury Mariner hybrid just turned 81,000 miles. Same condition as the Audi as to leaks and use. Engines depend on lubrication to minimize wear during cold temperature starts. Synthetic and semi synthetic oils cling to engine parts with more persistence than mineral oils. I recommend a mechanic evaluate this engine to determine engine compression, oil pressure status and how clean the engine is by looking inside via the oil service port to detect sludge build up. IF you determine that all is well and you wish to change oils I recommend semi synthetic also known as synthetic blend motor oils. Much cheaper with just about the same performance in cold weather. I do recommend that for the first oil service that you change the oil after 30 days of use. Being super ultra detergent oil it will clean out any reside or sludge particles and needs to be drain and fresh oil replaced. Then replace every six months or 6,000 miles. Then, please monitor the oil quantity weekly. IF the oil quantity diminishes, sorry, this oil is not suitable.

Using Synthetic oils like AMSOIL will allow you to go 25,000 miles on the same oil and filter as well as giving you a 6% savings in fuel. AMSOIL will keep your vehicle running at Supreme Performance/Durability/Economy.

My SUV Exterra, has 197,000. my mechanics says as long as you keep maintenance, regular oil change and check,car will last. I own this since 2002 and in good running condition. Yours should do the same if you do regular maintenance, just like our body we need to maintain due go age. Good Luck.

Faster flow on cold start, more and better anti-wear and detergent additives. Older engines benefit even more than newer engines because they have more blow by so additives in conventional oil get used up faster. Read this article on synthetic

http://ricksfreeautorepairadvice.com/syn...