time/mileage/extended drains

[Tripple1]

Been reading a lot about extended drains with both conventionals and synthetics. It all sounds great, and I'm interested in extending mine as well.
Both my cars state in the owners manual to adhere to 3 month/3k for severe driving conditions which I fall under. Warrenty does not apply to either vehicle. I was interested to know if most of you who extend your drains have manuals that state 3 month or 3k for severe service? And is it best to follow the manual? Newer vehciles that recomend longer drains...are their engine specs and tolerances the same as what I have which was built in 1995, the other 2000?

 

[aquariuscsm]

My manual states to use the 3000 mile/3 month OCI also. I usually end up going by the 3 month OCI.

 

[Tripple1]

Well, I also ask because I realize the Jiffy lubes push the 3mo/3k for profit; however, the manufacturer has no gain in recomending 3 mo/3k, so why do they? Do they know something about the importance of shorter OCI's vs extending that we don't?

 

[simple_gifts]

I think auto mfgs stay on the side of caution. You state they have nothing to gain by recommending a 3/3K interval, but in fact they do, reduced warranty costs and increased warranty denials.

 

[Robert1955]

Originally Posted By: simple_gifts
I think auto mfgs stay on the side of caution. You state they have nothing to gain by recommending a 3/3K interval, but in fact they do, reduced warranty costs and increased warranty denials.

As well as increased profit for you visiting them for your oil change.