Im planning on changing my oil this weekend and wanted to know if anyone had any advice on what weight i should use. Its a 99 with 86000 miles and im using royal purple oil. should i use 5W-30 or 10W-30 for the summer.... any other suggestions would be appreciated too.

 

I would use 5w-20 or 0w-20 (same thing if synthetic). Royal purple is pretty good stuff. Check out Alisyn Synthetics on eBay for the best stuff sold. 5w-20 is also the recommended oil. You don't really need to go with a heavier oil in the summer nowadays, just use the recommended viscosity and your car will love it......Especially Synthetic!

Vince

 

5W-30 is what I use. Would I benfit more from the 5W-20?

 

ya know what, I run 5w30 motorcraft year round. My mechanic said to run 10W30 in the summer. I would never run 5W20, but thats just me. Especially if you have 86000 miles.

 

5w-30 synthetic ftw

 

I run 10w30 everytime. Just something I've always done, and probably wont ever change.

 

I think 5w30 is ok. The problem with 10w30 in our cars is that on most modern engines the oil passages are much smaller than they are on older design engines.Smaller oil passages,the superior lubrication and head index rating of modern motor oils, and tighter tolerances in engines thatcurrent technology provides are all reasons for many manufacturers specification of lower viscosity engine oil.

Here's how I see it from a professional dragracing standpoint: If your engine is capable of running a lower viscosity oil without sacrificing longevity or reliability, why go with a heavier weight oil and lose power, lose fuel economy, and actuallyput more wear on the engine due to reduced oil flow?

In one of my race bikes, a 2005 Suzuki GSX-R1000, we use <<0w (less than zero weight) synthetic without any side effects besides 6-7 extra horsepower IN A 1000CC (1.0L) ENGINE! (this is over conventional oil, about 3 over mobil 1) It's a stock internallyand comes with a 12.5:1 compression ratio and turns 13,500 rpm and makes 180hp to the wheel.

I'm not saying to use <<0w in your Mustang, I'm just saying don't be afraid of 5w20 or 0w20!!! (which is the EXACT same thing)

My 2002 GT has 91k on it and I use synthetic 0w20 and it runs like a champ!

Make more power, lose nothing!

Vince

Oh, and things are a little different if you are FI or use nitrous heavily.

 

I run 5w-20, just like the owner manual suggests. Why go againest the people that built your car??