Redline for my 1.8 (5w-30 or 5w-40)

Not open for further replies.
Oct 20, 2002
San Diego, CA

Originally posted by Jeffrey Behr:
...use the 5W-30. It has NO Viscosity-Index Improvers (VIIs), which are a slight performance compromise, whereas the 5W-40 has some (to get to '40' when hot).

My theoretical tribology isn't quite good yet, but a hypothetical based upon this.

If 5w-30 has no VIIs, what does 10w-30 use as a basestock? It has a lower VI but the same HT/HS Vis. Is it simply just a 'thicker' (when cold) POE molecule?


edit: for clarification

[ January 23, 2004, 02:10 PM: Message edited by: Ferb ]
Do a search for Redline in the UOA section and check out the VW 1.8T results Ive posted....
I'd run either the Redline 5w-30 or their 10w-30, which is essentially the same oil with a slightly thicker basestock.

The Redline 5w-40 is excellent, but it's insane to run an oil with a high temp/high shear viscosity of 4.7 Centipoise in 99% of stock street engines - for an air cooled 911, I'd run the 5w-40. The Redline 5w-40 is thick enough to use in an air cooled Harley, so it's too thick to get the best performance in this application. By best performance, I mean the lowest oil temps and the highest fuel efficiency and power - particularly at high rpms.

When it comes to the leading synlubes - thicker is NOT necessarily better!!!

I appreciate your input. It's nice to see that you recommend the Redline product even though you appear to be associated with Amsoil. That says a lot about you and makes what you say even more credible.
So even though the car will be chipped and it is a turbo, you think the 30 is the best move?
I have Redline 5W40 in my 2003 Toyota Camry. TO date it has seen -2F temps and a lot of 4F and 7F cold starts. It starts up with just barley a tap of the key. It rev's just as quickly as when I had 10W30 in dureing the summer! It is quite and silky smooth!

I have not done a UOA with this oil yet but plan on dropping this batch once I hit 7500 miles. It still looks like new at just under 5000 miles! I say try them both! I like the 5W40 and think it is a great comprimise for year round use! Their is nothing wrong with 10W30 though it too should protect great!
I'd go with the 5W-40. The VIIs don't scare me, and I'd kill for that HTHS. I doubt you'll feel a power difference between a 5W-30 and a 5W-40 oil. Butt dyno will feel a 10 hp difference, but not one of 0.2 hp or so.
wait... I was reading about some stuff the other day, and posts by molakule and bob led me to believe that synthetic oils start with a high inherent viscosity, i.e. a 5w-40 oil is a 40wt, that MAY need VIIs to make it act a certain way on the cold end. Dino oils need to have VIIs to make them perform on the thick (hot) end. SO I am not so sure that the 40 shearing to 30 is a big deal with a 5w-40.
Ive seen the 0w-40 M1 shear down, but thats an odd oil. Im not so sure about others liek redline.

Ok forgive me being an indecisive newbie but...
I HAD finally come to the decision about using Auto Rx and then going with the Redline 5w-40 oil in my passat based on feedback from all the great people on this site.
When I inquired to Redline about which viscosity to use they recommended the 5w-30 instead. Now I am a little confused as the the best for my engine. The reasoning was that both oils met the VW spec but the 30 would be cooler and have quicker start up, where the 40 would be slower/quieter.
Can anyone recommend or give me a good comparison of the two oils and which oil to use in my mild Seattle climate with a chipped daily commuter with 40K miles on it?

I was also recommended to use the redline gas additive...any thoughts there?

indecision may, or may not, be my problem right?

thanks for helping out

Don't worry about questioning your oil's all a part of the process!

With the 1.8, I'd definitely use the 40-weight...VW specs the oil and with the turbo, higher heat, small oil capacity, and "hard" driving, it makes sense to me. Plus, the 40-weight might just make it run smoother and quieter! The 5w-40 should also be just fine for your Seattle weather conditions.

I would use a fuel system/injector cleaner, such as the Redline, once every 10K right before an oil change.
Seriously, if you're not running your engineoil at extremely high temps, as you would be if you climbed mountains passes full throttle for many minutes, towed something, drove it on race tracks, etc., use the 5W-30. It has NO Viscosity-Index Improvers (VIIs), which are a slight performance compromise, whereas the 5W-40 has some (to get to '40' when hot). IMO you've picked the right brand--the 5W-30's High-Temperature, High-Shear (HTHS) result of 3.8 is 23% better than that of Mobil 1 5W-30.
I agree with Ted (TS) on this one.

This is not exactly the same thing, but I was running M1 0W-40 in my SAAB turbo and recently switched to GC (0W-30), both rated A3 (HT/HS > 3.5)

I know they're different chemistries, but with the thinner GC 0W-30, the engine runs a bit smoother, is more willing to rev, and there's better turbo response.

I'm thinking Redline 5W-30 would improve upon that even more, and it has a more than adequate HT/HS viscosity for protection... I'll probably try RL 5W-30 next.
I think using either 5w-30 or 5w-40 Redline will give you more protection than you'll ever need. Beyond that, you might get a few more warm fuzzies from running the thicker "high HTHS oil" or using some similar justification. It's just splitting hairs from here on out. I'd flip a coin and not burn any more brain cells.

If a coin flip won't work for you, I'd stick with Ted's advice and go with the 30 wt.

[ January 24, 2004, 04:26 PM: Message edited by: VeeDubb ]
I run 0W-30 Amsoil series 2000 in my turbocharged 1.8 Audi and i definately had great results. Cold starts are especially easy, and valvetrain noise was greatly reduced over the dino that came from the factory. Not sure if Redline is any better, but i chose the Amsoil just for better cold weather performance. Both i believe are good oils on paper. Although i have not seen many Redline UOA on these forums
Wow, all very helpful. I think it must be like the Ford vs Chevy debate. Perhaps I can't go wrong with either the 30 or the 40. But two answers were from oil manufacturers recommending the 30... so that does carry a lot of "weight" (no pun intended).
Any final helpful comments on 30 vs 40 redline before we put this post to bed?


Originally posted by Ferb:
Originally posted by Jeffrey Behr:
[qb If 5w-30 has no VIIs, what does 10w-30 use as a basestock? It has a lower VI but the same HT/HS Vis. Is it simply just a 'thicker' (when cold) POE molecule?
edit: for clarification
Well (and I could be wrong) I think conventional base stocks for say a 5W-30 are 4 cSt (@100C). Naturally VI improber is used to thet the 30 wt thickness and probably some pour point depressants as well for the lower end.

A 10W-30 PAO would simply use a 10 cSt oil (@100C)

As I said-someone corrrect me if I am wrong.
Not open for further replies.