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I've been contemplating using synthetic oil in my new truck. I was told that once I started to use synthetic, I had to stick with it. I was told that the individual properties of the two oils did not mix?
Does this sound right? I am also contemplating using it in my Honda's ......
when you switch over there is about a half of quart of "old" oil in the engine so they will mix anyway, don't worry about it. You will be pleased with the synthetic- they do sell "blends" of synthetic and reg. mineral oil to get the middle market so they do mix.
It's not a problem. I switched at 10,000 from whatever oil Dodge uses to Mobil 1 5w-30. I've picked up about 1 mpg since the switch. I'm also using a Mobil 1 filter.
No guys, I didn't do my first oil change at 10,000.
I switched to synthetic and have 200k since and no problems with the motor at all. I change filter every 4k and change oil and filter at 8k.
In response to your question about going back..... I was told you switch for life of the motor as there is something in the synthetic that bonds with the metal and if you were to take that away for an extended time then the metal would deteroriate more quickly. Of course this may happen anyway with natural oil. One of the many reasons I switched to synthetic.
I own a German car repair shop and there is no problem with mixing oils. The only possible downside is that the synthetic is thinner for a given viscosity and you might have some oil leaks that you don't have now. The additive package (detergents) see m to be a little more agressive in the synthetic and might attribute to the newly found leaks. The secret to engine longevity is how often you change the oil, not whether you use synthetic or petroleum based oil. If you are using it in your tow vehicle, change it every 3K, irregardless of the type of oil. Because the synthetic is thinner, it's not unusual to get a little better gas mileage. You have to figure if the benefits are worth the extra cost.
Barry
__________________ Capt. Barry
'04 Donzi 23ZF w/ '08 Verado 300
'04 John Sport 15 w/ '03 Johnson 90
I use synthetic in everything I own from my 2002 gmc to my twin 2002 330 HP Seamaxx inboards from day one. I even use it in my lawn mower. The only problem I have ever had is the damn motor out last the rest of the parts on the motor or vehicle. I have used syn. for at least 15 years. I would use it and never go back. I would however change the oil and filter together at 3000 to 4000 miles. I like this methode because at 3000 I start thinking about changing the oil and it gets done by 4000 miles. For boats every 50 hours. Amsoil seems to be the best for the price. Capt Rog
The Toyota dealer told my Dad not to put it in his Land Cruiser until he hit 100K. I don't think that makes any sense at all. I've used it in my last two vehicles (Toyota Tacoma and Jeep GC) and am a big believer. I am a bit of a PM freak though. I switch every 4k. I also use top shelf filters. I never have understood why anyone would pay the price for the oil but slap a $2-3 filter on their engine.
Definitely no problems mixing synthetic and "natural" oil. You just won't get all of the benefits. Some folks go to extended oil and/or filter change intervals. I would not recommend that until you have past your warranty period.
The only down side I have ever heard on synthetics (other than $$$) is that if you switch over on a high mileage engine, you may experience some leaks or increased oil consumption. This is because natural oil tends to make some seals swell (and seal better). The synthetic will allow the seals to shirink back to their "normal" size.* Mobil 1 claims to have solved this problem.
If you are planning on using synthetic in a diesel, make certain the oil has the proper API rating recommended by the manufacturer.* Mobil Delvac 1 is highly recommended for diesels on some web site.* Darn near impossibly to find but supposedly great stuff.
Amsoil is not API rated (no API starburst). If you have a problem, your manufacturer MAY deny warranty claims because of this. Amsoil claims they pay for the repairs, but I've never heard of anyone having had that happen (one way or the other). Mobil 1 OTOH carries the API testing Starburst, so you should be covered in all warranty cases.
I agree with danielb's point that there is still some residual oil left in the motor at the time you switch over to synthetic. Unless your willing to do a complete engine re-build at the time you switch from non-synthetic, to synthetic, I don't see how that can be avoided. Somewhere on the information on the oil container it should mention compatability issues (if any). From what I recall, Mobil 1 is compatable with most other oils.
I also agree with gibbs point about changing every 3k. When I change my Mobil 1 at 3k, it's just as black as a petroleum based oil.
Brad1 - Mobil1 "synthetic" is a petroleum based oil. They lost their lawsuit against Castrol, so they now sell an oil based on petroleum oil and call it a synthetic. It's pretty funny - they sue Castrol for doing it, lose, so now they do it themselves. If you can't beat 'em, join 'em!
The secret to engine longevity is how often you change the oil, not whether you use synthetic or petroleum based oil. Barry
Synthetic oil "IS" a petroleum based product made from Paraffinic Crude and not man made as some may think. I am a service director in a large Toyota dealer in Atlanta and sell both of the products from Castrol. The only difference in the two oils are the amount of refining that is done to produce the finished product. Synthetic oils have better additive packages normally and are better for your engine in my personal opinion. When using synthetic oils however, you still have to change it just as often as non-synthetic's because they collect just as much of the carbon deposits and dirt as the regular oil does and still lose their lubricating qualities just as fast. Conditions that you run you engine (towing, dusty conditions or high humidity) may make a difference in service intervals and cause a shorter mileage between changes. Mixing the oils is perfectly fine however, make sure you stick to the recomendations from the manufacture of the vehicle for the best lubrication in your climate.
Without getting into the chemical makeup of oil and what viscosity is, here is a simple way to understand oil and its ability to lubricate in different climates.
Most people think that the "W" (as in 10W30) in the oil's description stands for weight, however, the "W" stands for WINTER!!
The first number tells how well the oil will lubricate/flow in "Cold" temps and the second number tells how well the oil will lubricate/flow in "Hot" temptures. So, the lower the first number the better it will lubricate/flow in colder climates and the same for warmer temps on the second number that will be higher.
Mobil 1 is petroleum based. It is highly refined to weed out the short chain polymers, leaving only the longer more stable chains. This gives better protection against thermal breakdown and better lubricity.
Mixing Synthetic oil w/regular oil? 
. they mix with out a problem. 
