When it comes to oil, people usually say synthetic is better without really explaining why. My understanding is that it has a more consistent molecular weight, and resists shearing, both of which help maintain viscosity and lubricity as the oil ages. I've heard from some very smart people that if oil is fresh, synthetic and conventional do about the same job. So my question is this: is it okay to switch from expensive ($10 per quart) Mobil 1 to conventional oil if I change the oil more often?

My AP1 has about 160k miles, and although compression is okay (between 200 psi and 205 psi on all cylinders), blow-by is worse than a fresher engine, so the oil is going to get dirty more quickly. I therefore want to replace the oil more often. ALSO... I burn about a quart every 1000 miles. It's getting expensive to spend $100 on oil every 5000 miles or so. What harm would come from using conventional, especially if it gets refreshed with each 1000 mile top-up?

If you think I might run into issues, please explain why.

 

The only issue with conventional oil is varnish build up, but that happens when people leave it in the engine too long. Today's oil is much better engineered that way. My engine was varnished up when I bought the car, the previous owner said that he changed it religiously running non-synthetic Castrol With me running synthetic oil over the last 8 years it has cleaned up all of the varnish.

Conventional oil actually has better lubricity characteristics than synthetic oil from what I've read, 3,000 miles on conventional should work well.

 

Link it.

 

Mobil1 is known to burn excessively on our motors - you should try something else. Also you should be able to pick up a good quality synthetic on sale for $5-6/quart at your local auto store or walmart - Pennzoil Platinum, Castrol Syntec, etc

 

I ran Kendall GT-1 and Castrol GTX for years, in the Olden Days.

IMHO... no problems. As long as you pick a quality oil, do proper maintenance, and use an OEM filter.

 

Watch for rebates. I haven't paid more than $15 for a 5-quart jug of name brand synthetic in years. For $3 a quart, I'll stick with synthetic.

That said, I see no issue running conventional oil at 5K mile or less change intervals.

 

What can be said for pour point (maybe it's not an issue for you) and film strength?

 

you will be fine with conventional.

your engine will be in better shape with synthetic.

if you can afford it, get synthetic. if it really makes a difference financially, you'll be fine with conventional and frequent changes.

Walmart sells Mobil 1 cheap, as well as other brands synthetic. the 5 quart jugs are cheap at walmart.

 

$22 for a 5 quart jug of Mobil 1. $12 rebate / 5 quart jug.

I just got a check for $24 from Mobil 1.

My AP1 w/ 70K miles and now a track only machine burns almost no oil.

 

your AP1 is not real.