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Synthetic or Conventional Oil?

3K views 10 replies 5 participants last post by  skippy89 
#1 ·
Alright guys, as some of you might know, I'm putting a new engine in my truck, and my next question that i bring to the table is this. Synthetic or conventional oil, what do you use and why? I want to treat this engine right, and it all starts out there.
 
#5 ·
Use conventional oil with special break-in lube on the cam lobes for the engine break-in. After that you should use a high zinc content synthetic for the flat tappet cam.

The easiest oil to find for me has been Mobil 1 15w50 synthetic, which is formulated with 1200 ppm of zinc. I think this is the only weight of Mobil oil with the high zinc content, so don't expect the same from the other weights. Advance Auto and other parts stores carry 15w50, but Wal-Mart (usually the best price) does not stock that weight.

This link explains the zinc content for this oil.
http://www.mobiloil.com/usa-english...mobil/Zinc_Levels_15W50_Mobil_1_Products.aspx

Bruce
 
#6 ·
Here is the answer in the link.

Question:
What's the Zinc Level Mobil 1 15W-50?
Hello, I read your answer about ZDDP and phosphorus levels. You even list the phosphorus level in your table, but you show no listing for the level of zinc. Other oil companies also list their zinc level. I would like to know the zinc content in your 15W-50 oil. I would like the level for the gold cap and the silver cap separately. I drive a car that is over 20 years old and the answer is important to me. Thank you, Jerry

Answer:
The important element here is the phosphorus since it is the active antiwear additive. That's why we show phosphorus as well as zinc. The zinc content is in the range of 0.12 - 0.13 weight percent (1200 - 1300 ppm). (Mobil 1 Extended Performance 15W-50 [gold cap] was discontinued about May 2009.)

What I get from the answer is this. Mobile 1, with the gold cap did have the zinc and phosphorus needed, but it was discontinued in May of 2009.
So the version of Mobile 1 currently available (February 2012) is the silver cap bottle, and from the answer mobile gave, I am not 100% sure it has the required levels of zinc and phosphorus. If you use this oil, make sure it does have the stuff in it you need.

You will note I put a date in my post. Engine oils are changing formulations all the time. information that was valid, or is valid when I wrote this, is not valid in the future.

Choose your engine oil carefully. It is very possible your favorite brand of oil you used has changed, and may no longer be suitable for your flat tappet cammed engine.
 
#7 ·
The Mobil guy's answer that I pointed to on the web site is a little confusing. He talks about a discontinued gold cap product in the same sentence as the current silver cap product.

This table from Mobil (dated Oct 2011) shows the zinc level of Mobil 1 15w50 as 1300 ppm. The recommended applications include engines with flat tappet cams.

http://www.mobil.com/USA-English/MotorOil/Files/Mobil_1_Product_Guide.pdf

As I mentioned already, I have been using this oil because its relatively easy to find in the stores and it currently has the zinc specs I want. There may be other brands that are equivalent or better.

Bruce
 
#11 ·
against all odds said:
Which engine?
It's nothing to special, just a replacement long block assembly for my 1989 K 1500, It's a standard bore 350, 2 bolt main, 1 piece rear seal, 9:1 compression, flat tappet hydraulic cam .382 Int/ .402 Exh a mind blowing 200hp....haha although i have a performer intake manifold going on it, with a rebuilt TBI with adjustable pressure regulater, and a set of flowtech headers. Might tear into it and put a double roller chain in it, along with a bigger cam, but idk how big i can go before i have to reprogram the computer, which i don't want to do.
 
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