Synthetic oils so slippery they get by seals?

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Jan 13, 2003
I just bought a 1999 Mazda 626 with 31,000 miles on it,it's 4 cylinder automatic transmission,and the service tech at the dealer told me that synthetic oils like Amsoil are so slippery that it can get by seals causing leak and I was better off with non-synthetic and change oil every 3000 miles. Any truth to that? I did have a 1998 Honda Passport before with 133,000 miles on it when I traded,I used Amsoil for 90,000 miles,and the rear main seal did leak about a 1qt. of oil a month. I thought I would change over to Amsoil in the Mazda but now I'm not sure. I'm afriad of seal leaks. Thanks for all and any input. Robert L.
Robert, That individual is incorrect. Synth's are not so "slippery" that it will get by seals. Synth's in general tend to "clean" better and when switching to a synth from a non that may or may not have seals that have slight amounts of crud accumilated on them, insulating it from oil, tend to make them hard and not as plyable which in turn the synth cleans the seals, then the hard seal cannot keep a seal which the crude was doing all the sealing. This senerio depends on how that engine was maintained and the type of usage it has seen + mileage. On the 36k mile engine, you should have no problem with the oil passing by the seals using amsoil.
I don't think that's true. But some synthetics are more polar than others, creating an affinity for surfaces which causes it to try to separate them. Thus possibly causing additional weeping <i>on a poor seal</i>.
many thanx..I figured the slippery getting by seals was a bunch of bolognie. I"ll go with the Amsoil. I prefer the fewer drain intervals w/synthetics,since I drive about 60-80 miles a day 5 days a week. And with the synthetic less sludge build up when the engine has 80,000 plus miles on it. Thanks again. Robert L.
In the same vein with Bobs description, I was told by a Mobil tech that if you have been using a conventional oil that it never gets to some parts of the seals and when a synthetic is introduced it does some cleaning and gets to this part but by this time it is dried out so the leak ensues.
I know I'm gonna get some people upset, but since you did bring up the dealer, it sounds like he's not to pro synth's let alone amsoil. If the vehicle is underwarr, I'd suggest to use the xl7500 series oil that amsoil produces so not to void an warr's. The xl series oils is api certified and will not void the warr where as the series 2 and 3,000 are not api certified. Also, maintain recommended oil drains by the factory so that too doesn't get you a voided warr due to extended oil drains.. This is just a suggestion and a recommendation.
At the perils of starting a war over this again. I just today was looking for something in my 2002 F-Body GM Service manual and came accross this statement of interest (to me anyhow).
In areas of the world other than North America, it may be difficult to find oils that display the API STARBURST symbol. If you cannot find oils displaying the API STARBURST, look for oils that meet API Service SJ and ACERA A3-96 guidlines.
[ January 17, 2003, 05:41 PM: Message edited by: Mike ]
Mike, In the time since that owner's manual was printed, API has updated their current spec to SL, and ACEA has updated their top spec to A3-02. In any case, you'll only find ACEA A3 oils among the higher priced synthetic oils (including Mobil 1 0W-40 & 15W-50, not their xW-30 oils which are A5), and a very few moderately priced oils like Schaeffer 7000 oils. ACEA A3 oils are the best on the market, A5 is almost as good, and A1 is the usual stuff you find, including most oils with the Starburst symbol. Ken
4 Robert l Go ahead and use Amsoil 5w-30 or even 0W-30 in your vehicle. I have used Amsoil in both my 2 vehicles since about 300 mile mark w/no leaks and am very satisfied w/Amsoil products. I am plannining on installing dual remote oil filter systems from Amsoil in both vehicles pretty soon. Won't be no prob on my 98 CV LX HPP, however, on 2001 Nissan Pathfinder there is a lack of space, picking a spot is my main issue, but that shall be overcome w/some patience. Another thing with using dual remote, you can use larger filters which in-turn gives you more oil capacities and more filtering area etc., which is better for engine and checkbook in long run, plus piece of mind. By the way, you should go w/preferred customer deal from Amsoil, You can save a bunch on a years time by getting all your oil/filters etc thur them, you pay dealer cost plus minimal shipping. My 98 CV LX has 67000 miles and 01 Nissan has 22300 miles and no leaks, both purr like kittens at idle, no problems starting in cold SD. winter weather, fairly good mileage etc.. [ January 18, 2003, 10:00 AM: Message edited by: TOMBUCK ]
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