Originally Posted by VQLT
can I extend the OCI for an older car if I use today's modern oils? I have a 2005 Scion XA that recommends 6 months
or 5k miles but that is based on oil technology from 15 years ago (which I believe was SM rated oil). with new oils can I extend the OCI?
I went to 10K/1yr OCI three years ago on my wife's 2005 Ford Focus. Naturally aspirated, port injection, nothing fancy in the valve train.No complaints.
The justification for this lies in several ideas.
1.) Your car and mine, being EPA compliant and having a catalytic converter will have quality of combustion tightly controlled to protect the catalytic converter. This precise control of combustion and excellent ring sealing should mean minimal exhaust products getting into the oil, just like today's cars with 10K OCI.
2.) As for the 1 year part of it, 1 year has been appearing in many owners manuals for sometime.
3.) Higher TBN or higher TBN retention oils are widely available. I am comfortable with a starting TBN of 9 per ASTM D-2896, or lower with evidence of good retention.