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Discussion Starter #1 (Edited)
"randymo9" asked in this post:
what experience have people had with synthetic oils. have 2000 touring and only use conventional oil randy
I think this is a very interesting question. A quick glance at The Engine Oil Bible indicates there could be some serious risks switching to synthetic oils because:
  • it can "dislodge baked-on deposits",
  • it can "cause piston rings to leak and in some very rare cases, piston slap or crank vibration" and,
  • "mineral-oil-soaked gaskets and seals have been known to leak when exposed to synthetic oils."
For this reason, it recommends "don't switch to synthetic oil without preparation" but it doesn't seems to provide any further guidance for how to do that.

Please share you insights and experience.
 

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Supporting Vendor
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It should be noted that "synthetic" is a somewhat undefined term, and so what may be true for one oil may not hold with another.

Most synthetics sold today really should be labeled as synthetic blends, but that's another discussion entirely.

I have switched many [Alfa] engines over to synthetic, and have never had a problem. Nonetheless, here's my procedure:

1) Pull the cam covers and suck out all the old oil in the cam galleys (it's a good idea to do this every couple of oil changes anyway).

2) *IF* the oil in the cam galleys looks really bad, or there is sludge buildup, then it would be a good idea to pull the lower pan and clean that as well.

3) Fill with synthetic and run a fairly short change interval (2,000 miles?), then change again.

4) Then, get on with life...
 

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Richard Jemison
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Caution on Synthetics In Alfa Motors

New synthetics have little or no anti-scuff additive (zink) which is extremely important in the cam/cam follower life of our motors. Most (Mobile 1 has none) have too little to be protective. Valvoline Syn & Valvoline Racing Syn seem to have an adequate amount, but the racing oil has inadequate cleaning & disbursants.
The safest bet is to stick with Diesel formulations such as Shell Rotella, or similar oils.
Check out the second section of:
http://www.atis.net/oil_faq.html
 

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New synthetics have little or no anti-scuff additive (zink) which is extremely important in the cam/cam follower life of our motors.
Sorta off topic but here goes anyway:

There has been an abnormal flat tappet cam failure rate in Chevy engine rebuilds because of the change in formulation of modern engine oils. It is recommended to use Diesal (non syn) oils like Rotella, Delvac and Delo. Info obtained from :eek: "Hot Rod Magazine" and I think Crane cams also had input to the article.
 

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Sorta off topic but here goes anyway:

There has been an abnormal flat tappet cam failure rate in Chevy engine rebuilds because of the change in formulation of modern engine oils. It is recommended to use Diesal (non syn) oils like Rotella, Delvac and Delo. Info obtained from :eek: "Hot Rod Magazine" and I think Crane cams also had input to the article.
Here is a link to the Hot Rod article..

http://www.hotrod.com/techarticles/engine/flat_tappet_cam_tech/

Having read the article, it looks like the use of synthetics in older engines is only a problem with newly rebuilt engines in the first hours of running. An older 'broken in" engine will have no wear problems regardless of the oils chemistry.

Dave
 

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But Mad North-Northwest
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New synthetics have little or no anti-scuff additive (zink) which is extremely important in the cam/cam follower life of our motors. Most (Mobile 1 has none) have too little to be protective.
Okay, a few things. First, the zinc issue is not solely a synthetic issue but is a problem with most newer SM oils, synthetic or conventional. Secondly, your statement that Mobil1 has no zinc is completely wrong. Mobil1 has always had ZDDP additives. When they went to the SM formulation for the extended performance oil the zinc levels did drop (in line with what happened with most of the other SM oils...something like 1400 -> 900 ppm or so) but it's still there.

Also, these ZDDP changes will be coming soon to the diesel oils as well, so don't get complacent.

The new silver top Mobil1 15W50 SM (the non extended performance version) is claimed to have 1200 ppm zinc - which should be fine for flat tappets - and therefore would be one of the few SM oils to have enough zinc. I have not yet seen an oil analysis of it yet, however, so this number is hearsay.

As for the original question, I swapped both my cars over to synthetic with no issues (at ~85k on the Spider) but admittedly I'm dealing with much newer cars here than tubut's asking about.
 
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