2manyToyz

So the z's got almost 178K and running 10/40 QS and going strong. What d'ya think about going synth or just stick with regular maybe high mileage type? Also what about staying at the same weight or going 20/50. This is strictly street driving with a few WOT every now and then.

Kevin Blown 95 TA

10-40 dino

rexcellent

I would stick with conventional with that many miles on the motor. Sometimes switching over to synthetic will cause some leaks to surface that would go unnoticed w/ conventional oil.

Z-RATED94

I'm with the last two guys. Stick with what have.

bombebomb

At 178k miles and no racing in mind, no reason not to use dyno oil at this point.

This could start a huge debate that never ends obviously, I kind of see it both ways.

NJ-LE

2manyToyz:

Since your current oil has gotten you this far successfully ("So the z's got almost 178K and running 10/40 QS and going strong") why change oil brand, type or weight? Unless you have unusually low oil pressure at idle or cruising down the interstate then changing to 20-50 of the same brand and type sounds very reasonable.

mrmint69

With that many miles I would be careful not to do much in radical changes. If it ain't broke don't fix it is my motto.

'94 Bad A Z28

Since you threw that out there, I'll start it off.


There is nothing wrong with changing from dyno oil to synthetic oil at any point, and you can actually go back and forth between the two if you wanted and not do any damage. The only "problem" that there is when changing from conventional (dyno) oil to synthetic oil on a high mileage motor is that synthetic oil is created in a lab... Therefor there is no natural waxes in the oil like in dyno oil.


All that means is that anywhere there is a seal, a coupling, or anything that ties the oiling system together there is potential for an oil leak. There is this potential because these areas have never actually been "oiled" but rather caught all the waxes and impurities in the conventional oil all these years creating a build up blocking these areas from being oiled, which over the years causes these areas to "dry out."


Now you are introducing an "oil" created in a lab. This "oil" has no impurities, no oil, nothing that is in conventional oil besides lubrication and viscosity. This "clean oil" is now going to "clean" out your entire oiling system. Over time it will remove all that build up that has occurred over the years of using conventional oil. Once your oiling system has been "cleaned" synthetic oil will find every spot that it can to "leak" from all these spots that have never been oiled.


Long story short, you can do it if you want, but you will most likely see oil leaks that were "not there" before.


Eddie

Injuneer

Stay away from the "20W" viscosity designation. That means the oil is thicker when the engine is cold, and will not circulate as well as a "5W" or a "10W". A large part of engine wear occurs when the oil is cold, so you want the oil to flow well at low temperatures. That's what the "W" designates - how well the oil flows at low temps.

The primary advantage of synthetics is the increased ability to withstand high engine temperatures without coking and breaking down. Another is the ability to withstand breakdown of the molecular structure over periods of extended use. Since you appear to have a "stockish" engine, and don't subject to abuse at the track, and since the conventional oil you have been using has proven to meet your driving conditions well (appears you change it frequently), stick with it.

2manyToyz

Thanks fellas, I appreciate the knowledge y'all shared here. I'll stick with the 10 40 QS conventional, and change oil and filter every 1k like I've been doing.

z275plus

I thought the QS oil was bad for our engines.

camarobird92

You change your oil at 1k intervals? That seems a little overkill, but it has worked well for you.

bombebomb

It all makes sense now. (I accidentally cut off to much of your post)