STP Oil Treatment for Diesel Engines 3000 ml, Protects your Engine by Reducing Deposits, Reduced Oil Consumption, Mechanical Car Cleaning Products, Made in the UK

I have a 2019 Vauxhall Grandland X with a noisy engine. I was recommended this as a cheap way to try and fix the issue. I followed the instructions adding this to a warm engine that had time to settle. To my amazement it stopped the noisy knocking engine within about 30 seconds. I have now been running this for a few thousand miles and the engine is smoother and quieter. Definitely worth the money.

What a fantastic product.In the past I have always used SLICK 50, but wanted to see what else was out there to help protect my Mercedes engine. I looked at a few reviews and picked on this. For the price I was not expecting much considering how much I spend on other oil additives.The bottle arrived in the timescale promised, and well packaged.I had just had the car serviced and wanted to add a bit of protection to the engine. The instructions said I could add it to the oil and as the bottle is not too large I took the chance and began to pour into the engine.First thing that surprised me was that it was like a gel and not like an oil. I poured the additive in. I made the mistake of pouring it in like an oil, which soon filled the spout to the engine. Please when you use this pour VERY SLOWLY. This will stop the spout getting blocked.I have now driven the car for a couple of hundred miles and the engine is so much quiter. (Even the wife has noticed this)I cannot recommend this enough and I have had all sorts of cars over the last few of decades and this has been my best car based purchase.I hope this helps with your choice

Engine seems to be quieter after adding to car

SUPER DUPER HappyYES

I add this to the oil in my 1985 Ford Capri to protect the camshaft from the wear it's so notorious for. The reason is that this original thick gooey STP in the blue bottle is one of the few oil additives that still contains ZDDP, the magic anti-wear ingredient essential for older vehicles, but removed from modern oils in case any blow-by gets burnt and damages emissions equipment (primarily the catalytic converter). This is why STP have made the new version in the black bottle for modern cars. Seeing as my Capri doesn't have a catalytic converter, I just need loads of ZDDP and this is a cheap way of adding it to modern oil. I put 10w/40 in the Capri, and from a few simple tests timing a gallon draining through a small funnel, it looks like adding this to 10w/40 oil changes it pretty-much into 20w/50 oil (I have some lying around to compare). This agrees with the change in reading from the car's oil pressure meter at idle. The car idles smoothly and quietly with this additive in, and when I take the rocker cover off to adjust the valve clearances, the scoring on the camshaft doesn't appear to be getting any deeper.

Didn't really believe the reviews as this is the first time using a product like this but I can honestly say my engine seems to run smoother and not as loud. What I did is place the oil treatment bottle in a container of hot water (again in the bottle not diluted with water..) to make it more runny and take my car on a 20 minute drive to get the oil flowing and warmed. Came back put the full bottle in (Audi a5 3.0 tdi ~7-7.5L engine oil) so could have got away with 1 1/2 bottles of this but didn't want my oil to be too thick due to it being winter! Then went on another 30 minute drive and within 10-15 minutes I could tell my engine felt as it was running smoother and not as loud. Engine seemed more responsive but that could also be due to running a cycle of STP injection cleaner in my tank. Just a tip wear gloves as it's a pain to get off your skin 🤔

Seems good

It's very thick so let it warm in a bowl of boiled water for a few minutes first. This lets it flow better out of the bottle.It's well worth looking after the engine. These are the things that prolong the life of the car