Synthetic or Conventional?

[II kings 9:20]

Well guys, one of the girls at work has a Concorde 2.7, 50K that needs a new engine because of sludge. I googled and found lots of info on the 2.7 sludge problem "Engine oil sludge is due to what several engine experts have stated is due to engine oil passages that are too narrow for engine oil to properly circulate causing the oil to cook inside the engine with falure occurring as early as 35K with average failure at 50K". This is why synthetic oil is better, heat resistance is superior and "cooking" it (without a blow torch) is extremely difficult.

[james jefferson]

Originally Posted by Abshear7

FYI, I mentioned the change to synthetic to my dealer on Friday and was advised not to do it; service mgr. stated that the MDS system may or may not be affected differently by a different type of oil, so safer to stay with mfr. recommended. Not sure how valid of a concern this is, but thought I'd pass it along.

balooney, MY dealer said they recommend using ONLY synthetic oil. guess it depends wheter the dealer has and is using synthetic oil. i use it.

[II kings 9:20]

One concern I have about various dealer recommendations is that they vary and many of these guys don't know what they are talking about which is I rely on the owners manual as the source for info. I use filter magnets and pan magnets not listed in the manual also. I find that many people in the auto svc. industry have'nt a clue on many topics. Specifically, using a torque wrench on the lug nuts. To a person when I have asked to have my lugs torqued to 80ftlb, the guy acts as if I am speaking Greek. Many have never heard of this. I explain that over torque can crack alloys, wear out brakes, and wear out wheel bearings, you should see the perplexed looks I get. Whenever I have tire svc I torque the lugs when I get home. I bent a lug wrench on a 300E changing out the Blizzaks that some idiot over torqued. A buddy was running through brakes on his Reatta every 15K and the dealer said it was the way he drove, a classic case of too tight lug nuts, not all cars are affected this way. Spark plugs similarly should be torqued, most have never heard of this. Bottom line is that many of the recommendations and practices of dealer services are flawed from a basic lack of knowledge. The owners manual says synthetic is OK regardless of what the service guy thinks. Most manuals do not mention any type of oil syn or reg, just weight and grade. I give DC credit for specifically stating syn is OK.

[james jefferson]

amen, the torqing of lug nuts is a concern of mine also, i don't know why mechanics dont take an extra 10 minutes and use torque wrench. i have had warped rotors on older cars due to over tightening lug nuts.

[E55 KEV]

In 1998 when the current Mercedes 3 valve/2 plugs modular engines debuted they did not specify oil. A few years later they were sued (class action) and had to offer coupons and increace engine warranties to all that used regular oil due to sludge buildup. Now the synthetic oil is mandatory.

[II kings 9:20]

Originally Posted by E55 KEV

In 1998 when the current Mercedes 3 valve/2 plugs modular engines debuted they did not specify oil. A few years later they were sued (class action) and had to offer coupons and increace engine warranties to all that used regular oil due to sludge buildup. Now the synthetic oil is mandatory.

I think this sums it up, as I stated in an earlier post, the cost difference is $233 over a 100K mile period. On a car that cost $38K it is really comical to talk about this as a cost issue, it's even comical to consider oil cost on my $800 Peugeot when spread over 100K miles.

[Paisan]

I'd wait til 3000 miles then go with Amsoil. I used to swear by Mobil 1 but started using Amsoil and really like the stuff.

-mike

[CottyGee]

The only Amsoil that is API certified is XL-7500.

http://eolcs.api.org/

[Paisan]

That's the one I use. Althought the higher grade ones are even better than that.

-mike

[II kings 9:20]

Guys, that Amsoil 5w20 7500XL is NOT full synthetic like the series 2000. They got a court order to allow them to call it synthetic, it is a reformulated conventional oil. I have both, the 7500 XL says "synthetic" and the 2000 says "100 % synthetic". There is a reason one is good for 25K and the other for 7.5K. I changed to the fake synthetic at 1900 and used the rest at 3K, won't buy any more, we have had a great discussion on the Thoughts on synthetic thread with 168 posts. I too am a Mobil 1 fan but no 5w20, the choices for 100% syn 5w20 are few, Castrol Syntec (my choice), Redline and Royal Purple. There may be others.