Trust my car's oil life gauge or get it changed every 3,000 miles?

[TheUnk]

What about oil age? If you let your car sit for 3+ months after say only 1k miles since the last change, should that impact when you should change it next?

 

[BurnItDwn]

I use full synthetic and change every 7500 miles.

 

[Pariah]

That's why I change my oil every 100 miles. Just to be safe.

Really? Are you an idiot? What kind of car enthusiast would admit that they sometimes make more than one trip in their car without changing the oil? If you hate your car so much that you can't be bothered to change the oil every time you use it, why even bother owing one? Maybe a forum dedicated to flower arranging would be more appropriate for you.

 

[michal1980]

if I wasn't sure of the history. I'd change it early. After that, go by the monitor.

 

[Mark R]

I don't agree with this.

What history exactly? Honda never had an oil interval of 12k miles until recently. It is WAY to premature to say anything supporting the new recommendations. I agree with others that 12k oil changes certainly will get you fine to 36k, or even 100k, but beyond? Who knows.

It's a lot to do with the new oil specifications too.

Older specifications required that after 100 hours of use, the oil manufacturer be able to demonstrate that an engine hadn't worn excessively and that the oil was between 50 and 150% of its specified viscosity.

More modern specifications not only specify maximum amount of piston/cam wear, but also require the oil to have at least 80% of its anti-wear additives remaining after 100 hours of high-load running, much stricter limits on viscosity shift, strict limits on deposit formation and new limits on sludge formation.

Historically, some oils had always exceeded the base specification, but its not practical for a car manufacturer to specify one particular brand of oil. So, service guidelines were typically set based upon the expected life-time of the minimum oil quality to meet specifications. In general, this would usually come out somewhere around 6000 miles.

In Europe where a lot of cars are business leases, the leasing companies have been harassing the OEMs for longer service intervals, ideally looking for 10-15k miles. So, a number of european manufacturers developed their own specifications for extended drain intervals. Some (e.g. VW) used infra-red indicator dyes as part of the formulation, which would degrade when the anti-wear additives depleted, and this would be detected by a spectrophotometer in the oil circuit, which would trigger the maintenance indicator.

There has been a trend in the industry to try to unify these specifications, as they cause problems with stock management and problems with engine/catalyst damage due use of the wrong grade. They have certainly caused a lot of confusion; for example if you go to a typical auto-parts shop and you want, for example, a Castrol Magnatec 5w30 - you'll find there are 4 or 5 different variants (one for BMW, one for VAG, one for PSA and one API generic).