Arthur wrote on 02/15/08 at 08:58:32:KwakNut, I always change my Mobil 1 every 3000 miles along with the filter, because I am concerned that since the car/motorcycle didn't start off new with Mobil 1, it likely has residual sludge in the oil pan or on other internal parts of the engine. My concern is that the Mobil 1 will start loosening these contaminants and allow them to harm the internals as they circulate. Was this subject addressed at Mobil?
Your caution is well thought out and logical – and I must admit I’ve always been a great advocate of preventative maintenance, so the idea of leaving oil in the sump for a long time was something that I didn’t embrace without a lot of convincing!
Mobil 1 isn’t chemically different to regular oils, it’s just ‘purer’ on a molecular level, so it’s more stable to physical and thermal breakdown, and produces less friction (& more protection).
It has a reasonably (but not excessively) strong detergent/dispersant package but it’s not going to suddenly strip crud out every nook and cranny of your motor.
I can see why you very sensibly want to be sure that previous oils haven’t left rubbish in there; for your own peace of mind, maybe you could change your first Mobil 1 fill after 3000 miles, then you can go to double book interval after.
Why do people change their oil so frequently? Probably because it’s only a few short years since we had to, and good habits are hard to get out of! Most of us were raised on brand-leading oils 20 or 30 years ago that were only as good as budget oils are now. Times and technology change, but it’s hard for us to change our outlook as quickly.
That said, it certainly can’t do your engine harm if you put fresh Mobil 1 in every 3000 miles, or even every 300 miles if it comes to it, but it just doesn’t need it and you’d be spending good money unnecessarily.
It’s like tyres. You have to change budget brands every 10,000 miles if you’re lucky because they wear out, while Michelins might last 30,000 – and give you a quieter ride and better grip at the same time. If you want you can change them when they’re only half worn – you could do, but why would you? Unlike with tyres, there’s no visual indicator that your oil still has plenty of life in it unless you spend about $100 on having it tested, and perhaps that’s why people are over-cautious..
One thing for sure, absolutely for sure, is that the guys who put Mobil 1 15/50 in their motor every 6000 or 10000 miles are looking after their engine better than the guys who religiously swap Walmart own brand every 1000!
When I buy a car or bike and don’t know that the previous owner has run it on synthetic, I give the engine a good flush.
I get it to running temperature with the old then drain it off (keeping the oil filter in place) and refill with 50/50 mix of cheap engine oil and paraffin to use as flush. I then run it for just 20-30 seconds at low revs (not at idle – go 2-3000rpm to ensure that the thinner mix is aquaplaning between cam and followers), turn off and leave it for 5 minutes to dissolve crud, run it for another 10-20 seconds then drain out – despite being fresh it comes out black.
Next stage is another fill with ordinary mineral oil and a 30 second run to flush the paraffin/oil mix out and remaining crap, drain again, change filters and fill with Mobil 1.
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